xref: /freebsd/contrib/tzcode/NEWS (revision ebacd8013fe5f7fdf9f6a5b286f6680dd2891036)
1News for the tz database
2
3Release 2022g - 2022-11-29 08:58:31 -0800
4
5  Briefly:
6    The northern edge of Chihuahua changes to US timekeeping.
7    Much of Greenland stops changing clocks after March 2023.
8    Fix some pre-1996 timestamps in northern Canada.
9    C89 is now deprecated; please use C99 or later.
10    Portability fixes for AIX, libintl, MS-Windows, musl, z/OS
11    In C code, use more C23 features if available.
12    C23 timegm now supported by default
13    Fixes for unlikely integer overflows
14
15  Changes to future timestamps
16
17    In the Mexican state of Chihuahua, the border strip near the US
18    will change to agree with nearby US locations on 2022-11-30.
19    The strip's western part, represented by Ciudad Juárez, switches
20    from -06 all year to -07/-06 with US DST rules, like El Paso, TX.
21    The eastern part, represented by Ojinaga, will observe US DST next
22    year, like Presidio, TX.  (Thanks to Heitor David Pinto.)
23    A new Zone America/Ciudad_Juarez splits from America/Ojinaga.
24
25    Much of Greenland, represented by America/Nuuk, stops observing
26    winter time after March 2023, so its daylight saving time becomes
27    standard time.  (Thanks to Jonas Nyrup and Jürgen Appel.)
28
29  Changes to past timestamps
30
31    Changes for pre-1996 northern Canada (thanks to Chris Walton):
32
33      Merge America/Iqaluit and America/Pangnirtung into the former,
34      with a backward compatibility link for the latter name.
35      There is no good evidence the two locations differ since 1970.
36      This change affects pre-1996 America/Pangnirtung timestamps.
37
38      Cambridge Bay, Inuvik, Iqaluit, Rankin Inlet, Resolute and
39      Yellowknife did not observe DST in 1965, and did observe DST
40      from 1972 through 1979.
41
42      Whitehorse moved from -09 to -08 on 1966-02-27, not 1967-05-28.
43
44    Colombia's 1993 fallback was 02-06 24:00, not 04-04 00:00.
45    (Thanks to Alois Treindl.)
46
47    Singapore's 1981-12-31 change was at 16:00 UTC (23:30 local time),
48    not 24:00 local time.  (Thanks to Geoff Clare via Robert Elz.)
49
50  Changes to code
51
52    Although tzcode still works with C89, bugs found in recent routine
53    maintenance indicate that bitrot has set in and that in practice
54    C89 is no longer used to build tzcode.  As it is a maintenance
55    burden, support for C89 is planned to be removed soon.  Instead,
56    please use compilers compatible with C99, C11, C17, or C23.
57
58    timegm, which tzcode implemented in 1989, will finally be
59    standardized 34 years later as part of C23, so timegm is now
60    supported even if STD_INSPIRED is not defined.
61
62    Fix bug in zdump's tzalloc emulation on hosts that lack tm_zone.
63    (Problem reported by Đoàn Trần Công Danh.)
64
65    Fix bug in zic on hosts where malloc(0) yields NULL on success.
66    (Problem reported by Tim McBrayer for AIX 6.1.)
67
68    Fix zic configuration to avoid linkage failures on some platforms.
69    (Problems reported by Gilmore Davidson and Igor Ivanov.)
70
71    Work around MS-Windows nmake incompatibility with POSIX.
72    (Problem reported by Manuela Friedrich.)
73
74    Port mktime and strftime to debugging platforms where accessing
75    uninitialized data has undefined behavior (strftime problem
76    reported by Robert Elz).
77
78    Check more carefully for unlikely integer overflows, preferring
79    C23 <stdckdint.h> to overflow checking by hand, as the latter has
80    had obscure bugs.
81
82  Changes to build procedure
83
84    New Makefile rule check_mild that skips checking whether Link
85    lines are in the file 'backward'.  (Inspired by a suggestion from
86    Stephen Colebourne.)
87
88
89Release 2022f - 2022-10-28 18:04:57 -0700
90
91  Briefly:
92    Mexico will no longer observe DST except near the US border.
93    Chihuahua moves to year-round -06 on 2022-10-30.
94    Fiji no longer observes DST.
95    Move links to 'backward'.
96    In vanguard form, GMT is now a Zone and Etc/GMT a link.
97    zic now supports links to links, and vanguard form uses this.
98    Simplify four Ontario zones.
99    Fix a Y2438 bug when reading TZif data.
100    Enable 64-bit time_t on 32-bit glibc platforms.
101    Omit large-file support when no longer needed.
102    In C code, use some C23 features if available.
103    Remove no-longer-needed workaround for Qt bug 53071.
104
105  Changes to future timestamps
106
107    Mexico will no longer observe DST after 2022, except for areas
108    near the US border that continue to observe US DST rules.
109    On 2022-10-30 at 02:00 the Mexican state of Chihuahua moves
110    from -07 (-06 with DST) to year-round -06, thus not changing
111    its clocks that day.  The new law states that Chihuahua
112    near the US border no longer observes US DST.
113    (Thanks to gera for the heads-up about Chihuahua.)
114
115    Fiji will not observe DST in 2022/3.  (Thanks to Shalvin Narayan.)
116    For now, assume DST is suspended indefinitely.
117
118  Changes to data
119
120    Move links to 'backward' to ease and simplify link maintenance.
121    This affects generated data only if you use 'make BACKWARD='.
122
123    GMT is now a Zone and Etc/GMT a link instead of vice versa,
124    as GMT is needed for leap second support whereas Etc/GMT is not.
125    However, this change exposes a bug in TZUpdater 2.3.2 so it is
126    present only in vanguard form for now.
127
128    Vanguard form now uses links to links, as zic now supports this.
129
130  Changes to past timestamps
131
132    Simplify four Ontario zones, as most of the post-1970 differences
133    seem to have been imaginary.  (Problem reported by Chris Walton.)
134    Move America/Nipigon, America/Rainy_River, and America/Thunder_Bay
135    to 'backzone'; backward-compatibility links still work, albeit
136    with some different timestamps before November 2005.
137
138  Changes to code
139
140    zic now supports links to links regardless of input line order.
141    For example, if Australia/Sydney is a Zone, the lines
142      Link Australia/Canberra Australia/ACT
143      Link Australia/Sydney Australia/Canberra
144    now work correctly, even though the shell commands
145      ln Australia/Canberra Australia/ACT
146      ln Australia/Sydney Australia/Canberra
147    would fail because the first command attempts to use a link
148    Australia/Canberra that does not exist until after the second
149    command is executed.  Previously, zic had unspecified behavior if
150    a Link line's target was another link, and zic often misbehaved if
151    a Link line's target was a later Link line.
152
153    Fix line number in zic's diagnostic for a link to a link.
154
155    Fix a bug that caused localtime to mishandle timestamps starting
156    in the year 2438 when reading data generated by 'zic -b fat' when
157    distant-future DST transitions occur at times given in standard
158    time or in UT, not the usual case of local time.  This occurs when
159    the corresponding .zi Rule lines specify DST transitions with TO
160    columns of 'max' and AT columns that end in 's' or 'u'.  The
161    number 2438 comes from the 32-bit limit in the year 2038, plus the
162    400-year Gregorian cycle.  (Problem reported by Bradley White.)
163
164    On glibc 2.34 and later, which optionally supports 64-bit time_t
165    on platforms like x86 where time_t was traditionally 32 bits,
166    default time_t to 64 instead of 32 bits.  This lets functions like
167    localtime support timestamps after the year 2038, and fixes
168    year-2038 problems in zic when accessing files dated after 2038.
169    To continue to limit time_t to 32 bits on these platforms, use
170    "make CFLAGS='-D_TIME_BITS=32'".
171
172    In C code, do not enable large-file support on platforms like AIX
173    and macOS that no longer need it now that tzcode does not use
174    off_t or related functions like 'stat'.  Large-file support is
175    still enabled by default on GNU/Linux, as it is needed for 64-bit
176    time_t support.
177
178    In C code, prefer C23 keywords to pre-C23 macros for alignof,
179    bool, false, and true.  Also, use the following C23 features if
180    available: __has_include, unreachable.
181
182    zic no longer works around Qt bug 53071, as the relevant Qt
183    releases have been out of support since 2019.  This change affects
184    only fat TZif files, as thin files never had the workaround.
185
186    zdump no longer modifies the environ vector when compiled on
187    platforms lacking tm_zone or when compiled with -DUSE_LTZ=0.
188    This avoid undefined behavior on POSIX platforms.
189
190
191Release 2022e - 2022-10-11 11:13:02 -0700
192
193  Briefly:
194    Jordan and Syria switch from +02/+03 with DST to year-round +03.
195
196  Changes to future timestamps
197
198    Jordan and Syria are abandoning the DST regime and are changing to
199    permanent +03, so they will not fall back from +03 to +02 on
200    2022-10-28.  (Thanks to Steffen Thorsen and Issam Al-Zuwairi.)
201
202  Changes to past timestamps
203
204    On 1922-01-01 Tijuana adopted standard time at 00:00, not 01:00.
205
206  Changes to past time zone abbreviations and DST flags
207
208    The temporary advancement of clocks in central Mexico in summer
209    1931 is now treated as daylight saving time, instead of as two
210    changes to standard time.
211
212
213Release 2022d - 2022-09-23 12:02:57 -0700
214
215  Briefly:
216    Palestine transitions are now Saturdays at 02:00.
217    Simplify three Ukraine zones into one.
218
219  Changes to future timestamps
220
221    Palestine now springs forward and falls back at 02:00 on the
222    first Saturday on or after March 24 and October 24, respectively.
223    This means 2022 falls back 10-29 at 02:00, not 10-28 at 01:00.
224    (Thanks to Heba Hamad.)
225
226  Changes to past timestamps
227
228    Simplify three Ukraine zones to one, since the post-1970
229    differences seem to have been imaginary.  Move Europe/Uzhgorod and
230    Europe/Zaporozhye to 'backzone'; backward-compatibility links
231    still work, albeit with different timestamps before October 1991.
232
233
234Release 2022c - 2022-08-15 17:47:18 -0700
235
236  Briefly:
237    Work around awk bug in FreeBSD, macOS, etc.
238    Improve tzselect on intercontinental Zones.
239
240  Changes to code
241
242    Work around a bug in onetrueawk that broke commands like
243    'make traditional_tarballs' on FreeBSD, macOS, etc.
244    (Problem reported by Deborah Goldsmith.)
245
246    Add code to tzselect that uses experimental structured comments in
247    zone1970.tab to clarify whether Zones like Africa/Abidjan and
248    Europe/Istanbul cross continent or ocean boundaries.
249    (Inspired by a problem reported by Peter Krefting.)
250
251    Fix bug with 'zic -d /a/b/c' when /a is unwritable but the
252    directory /a/b already exists.
253
254    Remove zoneinfo2tdf.pl, as it was unused and triggered false
255    malware alarms on some email servers.
256
257
258Release 2022b - 2022-08-10 15:38:32 -0700
259
260  Briefly:
261    Chile's DST is delayed by a week in September 2022.
262    Iran no longer observes DST after 2022.
263    Rename Europe/Kiev to Europe/Kyiv.
264    New zic -R option
265    Vanguard form now uses %z.
266    Finish moving duplicate-since-1970 zones to 'backzone'.
267    New build option PACKRATLIST
268    New tailored_tarballs target, replacing rearguard_tarballs
269
270  Changes to future timestamps
271
272    Chile's 2022 DST start is delayed from September 4 to September 11.
273    (Thanks to Juan Correa.)
274
275    Iran plans to stop observing DST permanently, after it falls back
276    on 2022-09-21.  (Thanks to Ali Mirjamali.)
277
278  Changes to past timestamps
279
280    Finish moving to 'backzone' the location-based zones whose
281    timestamps since 1970 are duplicates; adjust links accordingly.
282    This change ordinarily affects only pre-1970 timestamps, and with
283    the new PACKRATLIST option it does not affect any timestamps.
284    In this round the affected zones are Antarctica/Vostok,
285    Asia/Brunei, Asia/Kuala_Lumpur, Atlantic/Reykjavik,
286    Europe/Amsterdam, Europe/Copenhagen, Europe/Luxembourg,
287    Europe/Monaco, Europe/Oslo, Europe/Stockholm, Indian/Christmas,
288    Indian/Cocos, Indian/Kerguelen, Indian/Mahe, Indian/Reunion,
289    Pacific/Chuuk, Pacific/Funafuti, Pacific/Majuro, Pacific/Pohnpei,
290    Pacific/Wake and Pacific/Wallis, and the affected links are
291    Arctic/Longyearbyen, Atlantic/Jan_Mayen, Iceland, Pacific/Ponape,
292    Pacific/Truk, and Pacific/Yap.
293
294    From fall 1994 through fall 1995, Shanks wrote that Crimea's
295    DST transitions were at 02:00 standard time, not at 00:00.
296    (Thanks to Michael Deckers.)
297
298    Iran adopted standard time in 1935, not 1946.  In 1977 it observed
299    DST from 03-21 23:00 to 10-20 24:00; its 1978 transitions were on
300    03-24 and 08-05, not 03-20 and 10-20; and its spring 1979
301    transition was on 05-27, not 03-21.
302    (Thanks to Roozbeh Pournader and Francis Santoni.)
303
304    Chile's observance of -04 from 1946-08-29 through 1947-03-31 was
305    considered DST, not standard time.  Santiago and environs had moved
306    their clocks back to rejoin the rest of mainland Chile; put this
307    change at the end of 1946-08-28.  (Thanks to Michael Deckers.)
308
309    Some old, small clock transitions have been removed, as people at
310    the time did not change their clocks.  This affects Asia/Hong_Kong
311    in 1904, Asia/Ho_Chi_Minh in 1906, and Europe/Dublin in 1880.
312
313  Changes to zone name
314
315    Rename Europe/Kiev to Europe/Kyiv, as "Kyiv" is more common in
316    English now.  Spelling of other names in Ukraine has not yet
317    demonstrably changed in common English practice so for now these
318    names retain old spellings, as in other countries (e.g.,
319    Europe/Prague not "Praha", and Europe/Sofia not "Sofiya").
320
321  Changes to code
322
323    zic has a new option '-R @N' to output explicit transitions < N.
324    (Need suggested by Almaz Mingaleev.)
325
326    'zic -r @N' no longer outputs bad data when N < first transition.
327    (Problem introduced in 2021d and reported by Peter Krefting.)
328
329    zic now checks its input for NUL bytes and unterminated lines, and
330    now supports input line lengths up to 2048 (not 512) bytes.
331
332    gmtime and related code now use the abbreviation "UTC" not "GMT".
333    POSIX is being revised to require this.
334
335    When tzset and related functions set vestigial static variables
336    like tzname, they now prefer specified timestamps to unspecified ones.
337    (Problem reported by Almaz Mingaleev.)
338
339    zic no longer complains "can't determine time zone abbreviation to
340    use just after until time" when a transition to a new standard
341    time occurs simultaneously with the first DST fallback transition.
342
343  Changes to build procedure
344
345    Source data in vanguard form now uses the %z notation, introduced
346    in release 2015f.  For example, for America/Sao_Paulo vanguard
347    form contains the zone continuation line "-3:00 Brazil %z", which
348    is simpler and more reliable than the line "-3:00 Brazil -03/-02"
349    used in main and rearguard forms.  The plan is for the main form
350    to use %z eventually; in the meantime maintainers of zi parsers
351    are encouraged to test the parsers on vanguard.zi.
352
353    The Makefile has a new PACKRATLIST option to select a subset of
354    'backzone'.  For example, 'make PACKRATDATA=backzone
355    PACKRATLIST=zone.tab' now generates TZif files identical to those
356    of the global-tz project.
357
358    The Makefile has a new tailored_tarballs target for generating
359    special-purpose tarballs.  It generalizes and replaces the
360    rearguard_tarballs target and related targets and macros, which
361    are now obsolescent.
362
363    'make install' now defaults LOCALTIME to Factory not GMT,
364    which means the default abbreviation is now "-00" not "GMT".
365
366    Remove the posix_packrat target, marked obsolescent in 2016a.
367
368
369Release 2022a - 2022-03-15 23:02:01 -0700
370
371  Briefly:
372    Palestine will spring forward on 2022-03-27, not -03-26.
373    zdump -v now outputs better failure indications.
374    Bug fixes for code that reads corrupted TZif data.
375
376  Changes to future timestamps
377
378    Palestine will spring forward on 2022-03-27, not 2022-03-26.
379    (Thanks to Heba Hamad.)  Predict future transitions for first
380    Sunday >= March 25.  Additionally, predict fallbacks to be the first
381    Friday on or after October 23, not October's last Friday, to be more
382    consistent with recent practice.  The first differing fallback
383    prediction is on 2025-10-24, not 2025-10-31.
384
385  Changes to past timestamps
386
387    From 1992 through spring 1996, Ukraine's DST transitions were at
388    02:00 standard time, not at 01:00 UTC.  (Thanks to Alois Treindl.)
389
390    Chile's Santiago Mean Time and its LMT precursor have been adjusted
391    eastward by 1 second to align with past and present law.
392
393  Changes to commentary
394
395    Add several references for Chile's 1946/1947 transitions, some of
396    which only affected portions of the country.
397
398  Changes to code
399
400    Fix bug when mktime gets confused by truncated TZif files with
401    unspecified local time.  (Problem reported by Almaz Mingaleev.)
402
403    Fix bug when 32-bit time_t code reads malformed 64-bit TZif data.
404    (Problem reported by Christos Zoulas.)
405
406    When reading a version 2 or later TZif file, the TZif reader now
407    validates the version 1 header and data block only enough to skip
408    over them, as recommended by RFC 8536 section 4.  Also, the TZif
409    reader no longer mistakenly attempts to parse a version 1 TZIf
410    file header as a TZ string.
411
412    zdump -v now outputs "(localtime failed)" and "(gmtime failed)"
413    when local time and UT cannot be determined for a timestamp.
414
415  Changes to build procedure
416
417    Distribution tarballs now use standard POSIX.1-1988 ustar format
418    instead of GNU format.  Although the formats are almost identical
419    for these tarballs, ustar headers' magic fields contain "ustar"
420    instead of "ustar ", and their version fields contain "00" instead
421    of " ".  The two formats are planned to diverge more significantly
422    for tzdb releases after 2242-03-16 12:56:31 UTC, when the ustar
423    format becomes obsolete and the tarballs switch to pax format, an
424    extension of ustar.  For details about these formats, please see
425    "pax - portable archive interchange", IEEE Std 1003.1-2017,
426    <https://pubs.opengroup.org/onlinepubs/9699919799/utilities/pax.html#tag_20_92_13>.
427
428
429Release 2021e - 2021-10-21 18:41:00 -0700
430
431  Changes to future timestamps
432
433    Palestine will fall back 10-29 (not 10-30) at 01:00.
434    (Thanks to P Chan and Heba Hemad.)
435
436
437Release 2021d - 2021-10-15 13:48:18 -0700
438
439  Briefly:
440    Fiji suspends DST for the 2021/2022 season.
441    'zic -r' marks unspecified timestamps with "-00".
442
443  Changes to future timestamps
444
445    Fiji will suspend observance of DST for the 2021/2022 season.
446    Assume for now that it will return next year.  (Thanks to Jashneel
447    Kumar and P Chan.)
448
449  Changes to code
450
451    'zic -r' now uses "-00" time zone abbreviations for intervals
452    with UT offsets that are unspecified due to -r truncation.
453    This implements a change in draft Internet RFC 8536bis.
454
455
456Release 2021c - 2021-10-01 14:21:49 -0700
457
458  Briefly:
459    Revert most 2021b changes to 'backward'.
460    Fix 'zic -b fat' bug in pre-1970 32-bit data.
461    Fix two Link line typos.
462    Distribute SECURITY file.
463
464    This release is intended as a bugfix release, to fix compatibility
465    problems and typos reported since 2021b was released.
466
467  Changes to Link directives
468
469    Revert almost all of 2021b's changes to the 'backward' file,
470    by moving Link directives back to where they were in 2021a.
471    Although 'zic' doesn't care which source file contains a Link
472    directive, some downstream uses ran into trouble with the move.
473    (Problem reported by Stephen Colebourne for Joda-Time.)
474
475    Fix typo that linked Atlantic/Jan_Mayen to the wrong location
476    (problem reported by Chris Walton).
477
478    Fix 'backzone' typo that linked America/Virgin to the wrong
479    location (problem reported by Michael Deckers).
480
481  Changes to code
482
483    Fix a bug in 'zic -b fat' that caused old timestamps to be
484    mishandled in 32-bit-only readers (problem reported by Daniel
485    Fischer).
486
487  Changes to documentation
488
489    Distribute the SECURITY file (problem reported by Andreas Radke).
490
491
492Release 2021b - 2021-09-24 16:23:00 -0700
493
494  Briefly:
495    Jordan now starts DST on February's last Thursday.
496    Samoa no longer observes DST.
497    Merge more location-based Zones whose timestamps agree since 1970.
498    Move some backward-compatibility links to 'backward'.
499    Rename Pacific/Enderbury to Pacific/Kanton.
500    Correct many pre-1993 transitions in Malawi, Portugal, etc.
501    zic now creates each output file or link atomically.
502    zic -L no longer omits the POSIX TZ string in its output.
503    zic fixes for truncation and leap second table expiration.
504    zic now follows POSIX for TZ strings using all-year DST.
505    Fix some localtime crashes and bugs in obscure cases.
506    zdump -v now outputs more-useful boundary cases.
507    tzfile.5 better matches a draft successor to RFC 8536.
508    A new file SECURITY.
509
510    This release is prompted by recent announcements by Jordan and Samoa.
511    It incorporates many other changes that had accumulated since 2021a.
512    However, it omits most proposed changes that merged all Zones
513    agreeing since 1970, as concerns were raised about doing too many of
514    these changes at once.  It does keeps some of these changes in the
515    interest of making tzdb more equitable one step at a time; see
516    "Merge more location-based Zones" below.
517
518  Changes to future timestamps
519
520    Jordan now starts DST on February's last Thursday.
521    (Thanks to Steffen Thorsen.)
522
523    Samoa no longer observes DST.  (Thanks to Geoffrey D. Bennett.)
524
525  Changes to zone name
526
527    Rename Pacific/Enderbury to Pacific/Kanton.  When we added
528    Enderbury in 1993, we did not know that it is uninhabited and that
529    Kanton (population two dozen) is the only inhabited location in
530    that timezone.  The old name is now a backward-compatibility link.
531
532  Changes to past timestamps
533
534    Correct many pre-1993 transitions, fixing entries originally
535    derived from Shanks, Whitman, and Mundell.  The fixes include:
536      - Barbados: standard time was introduced in 1911, not 1932; and
537	DST was observed in 1942-1944
538      - Cook Islands: In 1899 they switched from east to west of GMT,
539	celebrating Christmas for two days.  They (and Niue) switched
540	to standard time in 1952, not 1901.
541      - Guyana: corrected LMT for Georgetown; the introduction of
542	standard time in 1911, not 1915; and corrections to 1975 and
543	1992 transitions
544      - Kanton: uninhabited before 1937-08-31
545      - Niue: only observed -11:20 from 1952 through 1964, then went to
546        -11 instead of -11:30
547      - Portugal: DST was observed in 1950
548      - Tonga: corrected LMT; the introduction of standard time in 1945,
549        not 1901; and corrections to the transition from +12:20 to +13
550        in 1961, not 1941
551    Additional fixes to entries in the 'backzone' file include:
552      - Enderbury: inhabited only 1860/1885 and 1938-03-06/1942-02-09
553      - The Gambia: 1933 and 1942 transitions
554      - Malawi: several 1911 through 1925 transitions
555      - Sierra Leone: several 1913 through 1941 transitions, and DST
556	was NOT observed in 1957 through 1962
557    (Thanks to P Chan, Michael Deckers, Alexander Krivenyshev and
558    Alois Treindl.)
559
560    Merge more location-based Zones whose timestamps agree since 1970,
561    as pre-1970 timestamps are out of scope.  This is part of a
562    process that has been ongoing since 2013.  This does not affect
563    post-1970 timestamps, and timezone historians who build with 'make
564    PACKRATDATA=backzone' should see no changes to pre-1970 timestamps.
565    When merging, keep the most-populous location's data, and move
566    data for other locations to 'backzone' with a backward
567    link in 'backward'.  For example, move America/Creston data to
568    'backzone' with a link in 'backward' from America/Phoenix because
569    the two timezones' timestamps agree since 1970; this change
570    affects some pre-1968 timestamps in America/Creston because
571    Creston and Phoenix disagreed before 1968.  The affected Zones
572    are Africa/Accra, America/Atikokan, America/Blanc-Sablon,
573    America/Creston, America/Curacao, America/Nassau,
574    America/Port_of_Spain, Antarctica/DumontDUrville, and
575    Antarctica/Syowa.
576
577  Changes to maintenance procedure
578
579    The new file SECURITY covers how to report security-related bugs.
580
581    Several backward-compatibility links have been moved to the
582    'backward' file.  These links, which range from Africa/Addis_Ababa
583    to Pacific/Saipan, are only for compatibility with now-obsolete
584    guidelines suggesting an entry for every ISO 3166 code.
585    The intercontinental convenience links Asia/Istanbul and
586    Europe/Nicosia have also been moved to 'backward'.
587
588  Changes to code
589
590    zic now creates each output file or link atomically,
591    possibly by creating a temporary file and then renaming it.
592    This avoids races where a TZ setting would temporarily stop
593    working while zic was installing a replacement file or link.
594
595    zic -L no longer omits the POSIX TZ string in its output.
596    Starting with 2020a, zic -L truncated its output according to the
597    "Expires" directive or "#expires" comment in the leapseconds file.
598    The resulting TZif files omitted daylight saving transitions after
599    the leap second table expired, which led to far less-accurate
600    predictions of times after the expiry.  Although future timestamps
601    cannot be converted accurately in the presence of leap seconds, it
602    is more accurate to convert near-future timestamps with a few
603    seconds error than with an hour error, so zic -L no longer
604    truncates output in this way.
605
606    Instead, when zic -L is given the "Expires" directive, it now
607    outputs the expiration by appending a no-change entry to the leap
608    second table.  Although this should work well with most TZif
609    readers, it does not conform to Internet RFC 8536 and some pickier
610    clients (including tzdb 2017c through 2021a) reject it, so
611    "Expires" directives are currently disabled by default.  To enable
612    them, set the EXPIRES_LINE Makefile variable.  If a TZif file uses
613    this new feature it is marked with a new TZif version number 4,
614    a format intended to be documented in a successor to RFC 8536.
615
616    zic -L LEAPFILE -r @LO no longer generates an invalid TZif file
617    that omits leap second information for the range LO..B when LO
618    falls between two leap seconds A and B.  Instead, it generates a
619    TZif version 4 file that represents the previously-missing
620    information.
621
622    The TZif reader now allows the leap second table to begin with a
623    correction other than -1 or +1, and to contain adjacent
624    transitions with equal corrections.  This supports TZif version 4.
625
626    The TZif reader now lets leap seconds occur less than 28 days
627    apart.  This supports possible future TZif extensions.
628
629    Fix bug that caused 'localtime' etc. to crash when TZ was
630    set to a all-year DST string like "EST5EDT4,0/0,J365/25" that does
631    not conform to POSIX but does conform to Internet RFC 8536.
632
633    Fix another bug that caused 'localtime' etc. to crash when TZ was
634    set to a POSIX-conforming but unusual TZ string like
635    "EST5EDT4,0/0,J365/0", where almost all the year is DST.
636
637    Fix yet another bug that caused 'localtime' etc. to mishandle slim
638    TZif files containing leap seconds after the last explicit
639    transition in the table, or when handling far-future timestamps
640    in slim TZif files lacking leap seconds.
641
642    Fix localtime misbehavior involving positive leap seconds.
643    This change affects only behavior for "right" system time,
644    which contains leap seconds, and only if the UT offset is
645    not a multiple of 60 seconds when a positive leap second occurs.
646    (No such timezone exists in tzdb, luckily.)  Without the fix,
647    the timestamp was ambiguous during a positive leap second.
648    With the fix, any seconds occurring after a positive leap second
649    and within the same localtime minute are counted through 60, not
650    through 59; their UT offset (tm_gmtoff) is the same as before.
651    Here is how the fix affects timestamps in a timezone with UT
652    offset +01:23:45 (5025 seconds) and with a positive leap second at
653    1972-06-30 23:59:60 UTC (78796800):
654
655	time_t    without the fix      with the fix
656	78796800  1972-07-01 01:23:45  1972-07-01 01:23:45 (leap second)
657	78796801  1972-07-01 01:23:45  1972-07-01 01:23:46
658	...
659	78796815  1972-07-01 01:23:59  1972-07-01 01:23:60
660	78796816  1972-07-01 01:24:00  1972-07-01 01:24:00
661
662    Fix an unlikely bug that caused 'localtime' etc. to misbehave if
663    civil time changes a few seconds before time_t wraps around, when
664    leap seconds are enabled.
665
666    Fix bug in zic -r; in some cases, the dummy time type after the
667    last time transition disagreed with the TZ string, contrary to
668    Internet RFC 8563 section 3.3.
669
670    Fix a bug with 'zic -r @X' when X is a negative leap second that
671    has a nonnegative correction.  Without the fix, the output file
672    was truncated so that X appeared to be a positive leap second.
673    Fix a similar, even-less-likely bug when truncating at a positive
674    leap second that has a nonpositive correction.
675
676    zic -r now reports an error if given rolling leap seconds, as this
677    usage has never generally worked and is evidently unused.
678
679    zic now generates a POSIX-conforming TZ string for TZif files
680    where all-year DST is predicted for the indefinite future.
681    For example, for all-year Eastern Daylight Time, zic now generates
682    "XXX3EDT4,0/0,J365/23" where it previously generated
683    "EST5EDT,0/0,J365/25" or "".  (Thanks to Michael Deckers for
684    noting the possibility of POSIX conformance.)
685
686    zic.c no longer requires sys/wait.h (thanks to spazmodius for
687    noting it wasn't needed).
688
689    When reading slim TZif files, zdump no longer mishandles leap
690    seconds on the rare platforms where time_t counts leap seconds,
691    fixing a bug introduced in 2014g.
692
693    zdump -v now outputs timestamps at boundaries of what localtime
694    and gmtime can represent, instead of the less-useful timestamps
695    one day after the minimum and one day before the maximum.
696    (Thanks to Arthur David Olson for prototype code, and to Manuela
697    Friedrich for debugging help.)
698
699    zdump's -c and -t options are now consistently inclusive for the
700    lower time bound and exclusive for the upper.  Formerly they were
701    inconsistent.  (Confusion noted by Martin Burnicki.)
702
703  Changes to build procedure
704
705    You can now compile with -DHAVE_MALLOC_ERRNO=0 to port to
706    non-POSIX hosts where malloc doesn't set errno.
707    (Problem reported by Jan Engelhardt.)
708
709  Changes to documentation
710
711    tzfile.5 better matches a draft successor to RFC 8536
712    <https://datatracker.ietf.org/doc/draft-murchison-rfc8536bis/01/>.
713
714
715Release 2021a - 2021-01-24 10:54:57 -0800
716
717  Changes to future timestamps
718
719    South Sudan changes from +03 to +02 on 2021-02-01 at 00:00.
720    (Thanks to Steffen Thorsen.)
721
722
723Release 2020f - 2020-12-29 00:17:46 -0800
724
725  Change to build procedure
726
727    'make rearguard_tarballs' no longer generates a bad rearguard.zi,
728    fixing a 2020e bug.  (Problem reported by Deborah Goldsmith.)
729
730
731Release 2020e - 2020-12-22 15:14:34 -0800
732
733  Briefly:
734    Volgograd switches to Moscow time on 2020-12-27 at 02:00.
735
736  Changes to future timestamps
737
738    Volgograd changes time zone from +04 to +03 on 2020-12-27 at 02:00.
739    (Thanks to Alexander Krivenyshev and Stepan Golosunov.)
740
741  Changes to past timestamps
742
743    Correct many pre-1986 transitions, fixing entries originally
744    derived from Shanks.  The fixes include:
745      - Australia: several 1917 through 1971 transitions
746      - The Bahamas: several 1941 through 1945 transitions
747      - Bermuda: several 1917 through 1956 transitions
748      - Belize: several 1942 through 1968 transitions
749      - Ghana: several 1915 through 1956 transitions
750      - Israel and Palestine: several 1940 through 1985 transitions
751      - Kenya and adjacent: several 1908 through 1960 transitions
752      - Nigeria and adjacent: correcting LMT in Lagos, and several 1905
753        through 1919 transitions
754      - Seychelles: the introduction of standard time in 1907, not 1906
755      - Vanuatu: DST in 1973-1974, and a corrected 1984 transition
756    (Thanks to P Chan.)
757
758    Because of the Australia change, Australia/Currie (King Island) is
759    no longer needed, as it is identical to Australia/Hobart for all
760    timestamps since 1970 and was therefore created by mistake.
761    Australia/Currie has been moved to the 'backward' file and its
762    corrected data moved to the 'backzone' file.
763
764  Changes to past time zone abbreviations and DST flags
765
766    To better match legislation in Turks and Caicos, the 2015 shift to
767    year-round observance of -04 is now modeled as AST throughout before
768    returning to Eastern Time with US DST in 2018, rather than as
769    maintaining EDT until 2015-11-01.  (Thanks to P Chan.)
770
771  Changes to documentation
772
773    The zic man page now documents zic's coalescing of transitions
774    when a zone falls back just before DST springs forward.
775
776
777Release 2020d - 2020-10-21 11:24:13 -0700
778
779  Briefly:
780    Palestine ends DST earlier than predicted, on 2020-10-24.
781
782  Changes to past and future timestamps
783
784    Palestine ends DST on 2020-10-24 at 01:00, instead of 2020-10-31
785    as previously predicted (thanks to Sharef Mustafa.)  Its
786    2019-10-26 fall-back was at 00:00, not 01:00 (thanks to Steffen
787    Thorsen.)  Its 2015-10-23 transition was at 01:00 not 00:00, and
788    its spring 2020 transition was on March 28 at 00:00, not March 27
789    (thanks to Pierre Cashon.)  This affects Asia/Gaza and
790    Asia/Hebron.  Assume future spring and fall transitions will be on
791    the Saturday preceding the last Sunday of March and October,
792    respectively.
793
794
795Release 2020c - 2020-10-16 11:15:53 -0700
796
797  Briefly:
798    Fiji starts DST later than usual, on 2020-12-20.
799
800  Changes to future timestamps
801
802    Fiji will start DST on 2020-12-20, instead of 2020-11-08 as
803    previously predicted.  DST will still end on 2021-01-17.
804    (Thanks to Raymond Kumar and Alan Mintz.)  Assume for now that
805    the later-than-usual start date is a one-time departure from the
806    recent pattern.
807
808  Changes to build procedure
809
810    Rearguard tarballs now contain an empty file pacificnew.
811    Some older downstream software expects this file to exist.
812    (Problem reported by Mike Cullinan.)
813
814
815Release 2020b - 2020-10-06 18:35:04 -0700
816
817  Briefly:
818    Revised predictions for Morocco's changes starting in 2023.
819    Canada's Yukon changes to -07 on 2020-11-01, not 2020-03-08.
820    Macquarie Island has stayed in sync with Tasmania since 2011.
821    Casey, Antarctica is at +08 in winter and +11 in summer.
822    zic no longer supports -y, nor the TYPE field of Rules.
823
824  Changes to future timestamps
825
826    Morocco's spring-forward after Ramadan is now predicted to occur
827    no sooner than two days after Ramadan, instead of one day.
828    (Thanks to Milamber.)  The first altered prediction is for 2023,
829    now predicted to spring-forward on April 30 instead of April 23.
830
831  Changes to past and future timestamps
832
833   Casey Station, Antarctica has been using +08 in winter and +11 in
834   summer since 2018.  The most recent transition from +08 to +11 was
835   2020-10-04 00:01.  Also, Macquarie Island has been staying in
836   sync with Tasmania since 2011.  (Thanks to Steffen Thorsen.)
837
838  Changes to past and future time zone abbreviations and DST flags
839
840    Canada's Yukon, represented by America/Whitehorse and
841    America/Dawson, changes its time zone rules from -08/-07 to
842    permanent -07 on 2020-11-01, not on 2020-03-08 as 2020a had it.
843    This change affects only the time zone abbreviation (MST vs PDT)
844    and daylight saving flag for the period between the two dates.
845    (Thanks to Andrew G. Smith.)
846
847  Changes to past timestamps
848
849    Correct several transitions for Hungary for 1918/1983.
850    For example, the 1983-09-25 fall-back was at 01:00, not 03:00.
851    (Thanks to Géza Nyáry.)  Also, the 1890 transition to standard
852    time was on 11-01, not 10-01 (thanks to Michael Deckers).
853
854    The 1891 French transition was on March 16, not March 15.  The
855    1911-03-11 French transition was at midnight, not a minute later.
856    Monaco's transitions were on 1892-06-01 and 1911-03-29, not
857    1891-03-15 and 1911-03-11.  (Thanks to Michael Deckers.)
858
859  Changes to code
860
861    Support for zic's long-obsolete '-y YEARISTYPE' option has been
862    removed and, with it, so has support for the TYPE field in Rule
863    lines, which is now reserved for compatibility with earlier zic.
864    These features were previously deprecated in release 2015f.
865    (Thanks to Tim Parenti.)
866
867    zic now defaults to '-b slim' instead of to '-b fat'.
868
869    zic's new '-l -' and '-p -' options uninstall any existing
870    localtime and posixrules files, respectively.
871
872    The undocumented and ineffective tzsetwall function has been
873    removed.
874
875  Changes to build procedure
876
877    The Makefile now defaults POSIXRULES to '-', so the posixrules
878    feature (obsolete as of 2019b) is no longer installed by default.
879
880  Changes to documentation and commentary
881
882    The long-obsolete files pacificnew, systemv, and yearistype.sh have
883    been removed from the distribution.  (Thanks to Tim Parenti.)
884
885
886Release 2020a - 2020-04-23 16:03:47 -0700
887
888  Briefly:
889    Morocco springs forward on 2020-05-31, not 2020-05-24.
890    Canada's Yukon advanced to -07 year-round on 2020-03-08.
891    America/Nuuk renamed from America/Godthab.
892    zic now supports expiration dates for leap second lists.
893
894  Changes to future timestamps
895
896    Morocco's second spring-forward transition in 2020 will be May 31,
897    not May 24 as predicted earlier.  (Thanks to Semlali Naoufal.)
898    Adjust future-year predictions to use the first Sunday after the
899    day after Ramadan, not the first Sunday after Ramadan.
900
901    Canada's Yukon, represented by America/Whitehorse and
902    America/Dawson, advanced to -07 year-round, beginning with its
903    spring-forward transition on 2020-03-08, and will not fall back on
904    2020-11-01.  Although a government press release calls this
905    "permanent Pacific Daylight Saving Time", we prefer MST for
906    consistency with nearby Dawson Creek, Creston, and Fort Nelson.
907    (Thanks to Tim Parenti.)
908
909  Changes to past timestamps
910
911    Shanghai observed DST in 1919.  (Thanks to Phake Nick.)
912
913  Changes to timezone identifiers
914
915    To reflect current usage in English better, America/Godthab has
916    been renamed to America/Nuuk.  A backwards-compatibility link
917    remains for the old name.
918
919  Changes to code
920
921    localtime.c no longer mishandles timestamps after the last
922    transition in a TZif file with leap seconds and with daylight
923    saving time transitions projected into the indefinite future.
924    For example, with TZ='America/Los_Angeles' with leap seconds,
925    zdump formerly reported a DST transition on 2038-03-14
926    from 01:59:32.999... to 02:59:33 instead of the correct transition
927    from 01:59:59.999... to 03:00:00.
928
929    zic -L now supports an Expires line in the leapseconds file, and
930    truncates the TZif output accordingly.  This propagates leap
931    second expiration information into the TZif file, and avoids the
932    abovementioned localtime.c bug as well as similar bugs present in
933    many client implementations.  If no Expires line is present, zic
934    -L instead truncates the TZif output based on the #expires comment
935    present in leapseconds files distributed by tzdb 2018f and later;
936    however, this usage is obsolescent.  For now, the distributed
937    leapseconds file has an Expires line that is commented out, so
938    that the file can be fed to older versions of zic which ignore the
939    commented-out line.  Future tzdb distributions are planned to
940    contain a leapseconds file with an Expires line.
941
942    The configuration macros HAVE_TZNAME and USG_COMPAT should now be
943    set to 1 if the system library supports the feature, and 2 if not.
944    As before, these macros are nonzero if tzcode should support the
945    feature, zero otherwise.
946
947    The configuration macro ALTZONE now has the same values with the
948    same meaning as HAVE_TZNAME and USG_COMPAT.
949
950    The code's defense against CRLF in leap-seconds.list is now
951    portable to POSIX awk.  (Problem reported by Deborah Goldsmith.)
952
953    Although the undocumented tzsetwall function is not changed in
954    this release, it is now deprecated in preparation for removal in
955    future releases.  Due to POSIX requirements, tzsetwall has not
956    worked for some time.  Any code that uses it should instead use
957    tzalloc(NULL) or, if portability trumps thread-safety, should
958    unset the TZ environment variable.
959
960  Changes to commentary
961
962    The Îles-de-la-Madeleine and the Listuguj reserve are noted as
963    following America/Halifax, and comments about Yukon's "south" and
964    "north" have been corrected to say "east" and "west".  (Thanks to
965    Jeffery Nichols.)
966
967
968Release 2019c - 2019-09-11 08:59:48 -0700
969
970  Briefly:
971    Fiji observes DST from 2019-11-10 to 2020-01-12.
972    Norfolk Island starts observing Australian-style DST.
973
974  Changes to future timestamps
975
976    Fiji's next DST transitions will be 2019-11-10 and 2020-01-12
977    instead of 2019-11-03 and 2020-01-19.  (Thanks to Raymond Kumar.)
978    Adjust future guesses accordingly.
979
980    Norfolk Island will observe Australian-style DST starting in
981    spring 2019.  The first transition is on 2019-10-06.  (Thanks to
982    Kyle Czech and Michael Deckers.)
983
984  Changes to past timestamps
985
986    Many corrections to time in Turkey from 1940 through 1985.
987    (Thanks to Oya Vulaş via Alois Treindl, and to Kıvanç Yazan.)
988
989    The Norfolk Island 1975-03-02 transition was at 02:00 standard
990    time, not 02:00 DST.  (Thanks to Michael Deckers.)
991
992    South Korea observed DST from 1948 through 1951.  Although this
993    info was supposed to appear in release 2014j, a typo inadvertently
994    suppressed the change.  (Thanks to Alois Treindl.)
995
996    Detroit observed DST in 1967 and 1968 following the US DST rules,
997    except that its 1967 DST began on June 14 at 00:01.  (Thanks to
998    Alois Treindl for pointing out that the old data entries were
999    probably wrong.)
1000
1001    Fix several errors in pre-1970 transitions in Perry County, IN.
1002    (Thanks to Alois Treindl for pointing out the 1967/9 errors.)
1003
1004    Edmonton did not observe DST in 1967 or 1969.  In 1946 Vancouver
1005    ended DST on 09-29 not 10-13, and Vienna ended DST on 10-07 not
1006    10-06.  In 1945 Königsberg (now Kaliningrad) switched from +01/+02
1007    to +02/+03 on 04-10 not 01-01, and its +02/+03 is abbreviated
1008    EET/EEST, not CET/CEST.  (Thanks to Alois Treindl.)  In 1946
1009    Königsberg switched to +03 on 04-07 not 01-01.
1010
1011    In 1946 Louisville switched from CST to CDT on 04-28 at 00:01, not
1012    01-01 at 00:00.  (Thanks to Alois Treindl and Michael Deckers.)
1013    Also, it switched from CST to CDT on 1950-04-30, not 1947-04-27.
1014
1015    The 1892-05-01 transition in Brussels was at 00:17:30, not at noon.
1016    (Thanks to Michael Deckers.)
1017
1018  Changes to past time zone abbreviations and DST flags
1019
1020    Hong Kong Winter Time, observed from 1941-10-01 to 1941-12-25,
1021    is now flagged as DST and is abbreviated HKWT not HKT.
1022
1023  Changes to code
1024
1025    leapseconds.awk now relies only on its input data, rather than
1026    also relying on its comments.  (Inspired by code from Dennis
1027    Ferguson and Chris Woodbury.)
1028
1029    The code now defends against CRLFs in leap-seconds.list.
1030    (Thanks to Brian Inglis and Chris Woodbury.)
1031
1032  Changes to documentation and commentary
1033
1034    theory.html discusses leap seconds.  (Thanks to Steve Summit.)
1035
1036    Nashville's newspapers dueled about the time of day in the 1950s.
1037    (Thanks to John Seigenthaler.)
1038
1039    Liechtenstein observed Swiss DST in 1941/2.
1040    (Thanks to Alois Treindl.)
1041
1042
1043Release 2019b - 2019-07-01 00:09:53 -0700
1044
1045  Briefly:
1046    Brazil no longer observes DST.
1047    'zic -b slim' outputs smaller TZif files; please try it out.
1048    Palestine's 2019 spring-forward transition was on 03-29, not 03-30.
1049
1050  Changes to future timestamps
1051
1052    Brazil has canceled DST and will stay on standard time indefinitely.
1053    (Thanks to Steffen Thorsen, Marcus Diniz, and Daniel Soares de
1054    Oliveira.)
1055
1056    Predictions for Morocco now go through 2087 instead of 2037, to
1057    work around a problem on newlib when using TZif files output by
1058    zic 2019a or earlier.  (Problem reported by David Gauchard.)
1059
1060  Changes to past and future timestamps
1061
1062    Palestine's 2019 spring transition was 03-29 at 00:00, not 03-30
1063    at 01:00.  (Thanks to Sharef Mustafa and Even Scharning.)  Guess
1064    future transitions to be March's last Friday at 00:00.
1065
1066  Changes to past timestamps
1067
1068    Hong Kong's 1941-06-15 spring-forward transition was at 03:00, not
1069    03:30.  Its 1945 transition from JST to HKT was on 11-18 at 02:00,
1070    not 09-15 at 00:00.  In 1946 its spring-forward transition was on
1071    04-21 at 00:00, not the previous day at 03:30.  From 1946 through
1072    1952 its fall-back transitions occurred at 04:30, not at 03:30.
1073    In 1947 its fall-back transition was on 11-30, not 12-30.
1074    (Thanks to P Chan.)
1075
1076  Changes to past time zone abbreviations
1077
1078    Italy's 1866 transition to Rome Mean Time was on December 12, not
1079    September 22.  This affects only the time zone abbreviation for
1080    Europe/Rome between those dates.  (Thanks to Stephen Trainor and
1081    Luigi Rosa.)
1082
1083  Changes affecting metadata only
1084
1085    Add info about the Crimea situation in zone1970.tab and zone.tab.
1086    (Problem reported by Serhii Demediuk.)
1087
1088  Changes to code
1089
1090    zic's new -b option supports a way to control data bloat and to
1091    test for year-2038 bugs in software that reads TZif files.
1092    'zic -b fat' and 'zic -b slim' generate larger and smaller output;
1093    for example, changing from fat to slim shrinks the Europe/London
1094    file from 3648 to 1599 bytes, saving about 56%.  Fat and slim
1095    files represent the same set of timestamps and use the same TZif
1096    format as documented in tzfile(5) and in Internet RFC 8536.
1097    Fat format attempts to work around bugs or incompatibilities in
1098    older software, notably software that mishandles 64-bit TZif data
1099    or uses obsolete TZ strings like "EET-2EEST" that lack DST rules.
1100    Slim format is more efficient and does not work around 64-bit bugs
1101    or obsolete TZ strings.  Currently zic defaults to fat format
1102    unless you compile with -DZIC_BLOAT_DEFAULT=\"slim\"; this
1103    out-of-the-box default is intended to change in future releases
1104    as the buggy software often mishandles timestamps anyway.
1105
1106    zic no longer treats a set of rules ending in 2037 specially.
1107    Previously, zic assumed that such a ruleset meant that future
1108    timestamps could not be predicted, and therefore omitted a
1109    POSIX-like TZ string in the TZif output.  The old behavior is no
1110    longer needed for current tzdata, and caused problems with newlib
1111    when used with older tzdata (reported by David Gauchard).
1112
1113    zic no longer generates some artifact transitions.  For example,
1114    Europe/London no longer has a no-op transition in January 1996.
1115
1116  Changes to build procedure
1117
1118    tzdata.zi now assumes zic 2017c or later.  This shrinks tzdata.zi
1119    by a percent or so.
1120
1121  Changes to documentation and commentary
1122
1123    The Makefile now documents the POSIXRULES macro as being obsolete,
1124    and similarly, zic's -p POSIXRULES option is now documented as
1125    being obsolete.  Although the POSIXRULES feature still exists and
1126    works as before, in practice it is rarely used for its intended
1127    purpose, and it does not work either in the default reference
1128    implementation (for timestamps after 2037) or in common
1129    implementations such as GNU/Linux (for contemporary timestamps).
1130    Since POSIXRULES was designed primarily as a temporary transition
1131    facility for System V platforms that died off decades ago, it is
1132    being decommissioned rather than institutionalized.
1133
1134    New info on Bonin Islands and Marcus (thanks to Wakaba and Phake Nick).
1135
1136
1137Release 2019a - 2019-03-25 22:01:33 -0700
1138
1139  Briefly:
1140    Palestine "springs forward" on 2019-03-30 instead of 2019-03-23.
1141    Metlakatla "fell back" to rejoin Alaska Time on 2019-01-20 at 02:00.
1142
1143  Changes to past and future timestamps
1144
1145    Palestine will not start DST until 2019-03-30, instead of 2019-03-23 as
1146    previously predicted.  Adjust our prediction by guessing that spring
1147    transitions will be between 24 and 30 March, which matches recent practice
1148    since 2016.  (Thanks to Even Scharning and Tim Parenti.)
1149
1150    Metlakatla ended its observance of Pacific standard time,
1151    rejoining Alaska Time, on 2019-01-20 at 02:00.  (Thanks to Ryan
1152    Stanley and Tim Parenti.)
1153
1154  Changes to past timestamps
1155
1156    Israel observed DST in 1980 (08-02/09-13) and 1984 (05-05/08-25).
1157    (Thanks to Alois Treindl and Isaac Starkman.)
1158
1159  Changes to time zone abbreviations
1160
1161    Etc/UCT is now a backward-compatibility link to Etc/UTC, instead
1162    of being a separate zone that generates the abbreviation "UCT",
1163    which nowadays is typically a typo.  (Problem reported by Isiah
1164    Meadows.)
1165
1166  Changes to code
1167
1168    zic now has an -r option to limit the time range of output data.
1169    For example, 'zic -r @1000000000' limits the output data to
1170    timestamps starting 1000000000 seconds after the Epoch.
1171    This helps shrink output size and can be useful for applications
1172    not needing the full timestamp history, such as TZDIST truncation;
1173    see Internet RFC 8536 section 5.1.  (Inspired by a feature request
1174    from Christopher Wong, helped along by bug reports from Wong and
1175    from Tim Parenti.)
1176
1177  Changes to documentation
1178
1179    Mention Internet RFC 8536 (February 2019), which documents TZif.
1180
1181    tz-link.html now cites tzdata-meta
1182    <https://tzdata-meta.timtimeonline.com/>.
1183
1184
1185Release 2018i - 2018-12-30 11:05:43 -0800
1186
1187  Briefly:
1188    São Tomé and Príncipe switches from +01 to +00 on 2019-01-01.
1189
1190  Changes to future timestamps
1191
1192    Due to a change in government, São Tomé and Príncipe switches back
1193    from +01 to +00 on 2019-01-01 at 02:00.  (Thanks to Vadim
1194    Nasardinov and Michael Deckers.)
1195
1196
1197Release 2018h - 2018-12-23 17:59:32 -0800
1198
1199  Briefly:
1200    Qyzylorda, Kazakhstan moved from +06 to +05 on 2018-12-21.
1201    New zone Asia/Qostanay because Qostanay, Kazakhstan didn't move.
1202    Metlakatla, Alaska observes PST this winter only.
1203    Guess Morocco will continue to adjust clocks around Ramadan.
1204    Add predictions for Iran from 2038 through 2090.
1205
1206  Changes to future timestamps
1207
1208    Guess that Morocco will continue to fall back just before and
1209    spring forward just after Ramadan, the practice since 2012.
1210    (Thanks to Maamar Abdelkader.)  This means Morocco will observe
1211    negative DST during Ramadan in main and vanguard formats, and in
1212    rearguard format it stays in the +00 timezone and observes
1213    ordinary DST in all months other than Ramadan.  As before, extend
1214    this guesswork to the year 2037.  As a consequence, Morocco is
1215    scheduled to observe three DST transitions in some Gregorian years
1216    (e.g., 2033) due to the mismatch between the Gregorian and Islamic
1217    calendars.
1218
1219    The table of exact transitions for Iranian DST has been extended.
1220    It formerly cut off before the year 2038 in a nod to 32-bit time_t.
1221    It now cuts off before 2091 as there is doubt about how the Persian
1222    calendar will treat 2091.  This change predicts DST transitions in
1223    2038-9, 2042-3, and 2046-7 to occur one day later than previously
1224    predicted.  As before, post-cutoff transitions are approximated.
1225
1226  Changes to past and future timestamps
1227
1228    Qyzylorda (aka Kyzylorda) oblast in Kazakhstan moved from +06 to
1229    +05 on 2018-12-21.  This is a zone split as Qostanay (aka
1230    Kostanay) did not switch, so create a zone Asia/Qostanay.
1231
1232    Metlakatla moved from Alaska to Pacific standard time on 2018-11-04.
1233    It did not change clocks that day and remains on -08 this winter.
1234    (Thanks to Ryan Stanley.)  It will revert to the usual Alaska
1235    rules next spring, so this change affects only timestamps
1236    from 2018-11-04 through 2019-03-10.
1237
1238  Change to past timestamps
1239
1240    Kwajalein's 1993-08-20 transition from -12 to +12 was at 24:00,
1241    not 00:00.  I transcribed the time incorrectly from Shanks.
1242    (Thanks to Phake Nick.)
1243
1244    Nauru's 1979 transition was on 02-10 at 02:00, not 05-01 at 00:00.
1245    (Thanks to Phake Nick.)
1246
1247    Guam observed DST irregularly from 1959 through 1977.
1248    (Thanks to Phake Nick.)
1249
1250    Hong Kong observed DST in 1941 starting 06-15 (not 04-01), then on
1251    10-01 changed standard time to +08:30 (not +08).  Its transition
1252    back to +08 after WWII was on 1945-09-15, not the previous day.
1253    Its 1904-10-30 change took effect at 01:00 +08 (not 00:00 LMT).
1254    (Thanks to Phake Nick, Steve Allen, and Joseph Myers.)  Also,
1255    its 1952 fallback was on 11-02 (not 10-25).
1256
1257    This release contains many changes to timestamps before 1946 due
1258    to Japanese possession or occupation of Pacific/Chuuk,
1259    Pacific/Guam, Pacific/Kosrae, Pacific/Kwajalein, Pacific/Majuro,
1260    Pacific/Nauru, Pacific/Palau, and Pacific/Pohnpei.
1261    (Thanks to Phake Nick.)
1262
1263    Assume that the Spanish East Indies was like the Philippines and
1264    observed American time until the end of 1844.  This affects
1265    Pacific/Chuuk, Pacific/Kosrae, Pacific/Palau, and Pacific/Pohnpei.
1266
1267  Changes to past tm_isdst flags
1268
1269    For the recent Morocco change, the tm_isdst flag should be 1 from
1270    2018-10-27 00:00 to 2018-10-28 03:00.  (Thanks to Michael Deckers.)
1271    Give a URL to the official decree.  (Thanks to Matt Johnson.)
1272
1273
1274Release 2018g - 2018-10-26 22:22:45 -0700
1275
1276  Briefly:
1277    Morocco switches to permanent +01 on 2018-10-28.
1278
1279  Changes to future timestamps
1280
1281    Morocco switches from +00/+01 to permanent +01 effective 2018-10-28,
1282    so its clocks will not fall back as previously scheduled.
1283    (Thanks to Mohamed Essedik Najd and Brian Inglis.)
1284
1285  Changes to code
1286
1287    When generating TZif files with leap seconds, zic no longer uses a
1288    format that trips up older 32-bit clients, fixing a bug introduced
1289    in 2018f.  (Reported by Daniel Fischer.)  Also, the zic workaround
1290    for QTBUG-53071 now also works for TZif files with leap seconds.
1291
1292    The translator to rearguard format now rewrites the line
1293    "Rule Japan 1948 1951 - Sep Sat>=8 25:00 0 S" to
1294    "Rule Japan 1948 1951 - Sep Sun>=9  1:00 0 S".
1295    This caters to zic before 2007 and to Oracle TZUpdater 2.2.0
1296    and earlier.  (Reported by Christos Zoulas.)
1297
1298  Changes to past time zone abbreviations
1299
1300    Change HDT to HWT/HPT for WWII-era abbreviations in Hawaii.
1301    This reverts to 2011h, as the abbreviation change in 2011i was
1302    likely inadvertent.
1303
1304  Changes to documentation
1305
1306    tzfile.5 has new sections on interoperability issues.
1307
1308
1309Release 2018f - 2018-10-18 00:14:18 -0700
1310
1311  Briefly:
1312  Volgograd moves from +03 to +04 on 2018-10-28.
1313  Fiji ends DST 2019-01-13, not 2019-01-20.
1314  Most of Chile changes DST dates, effective 2019-04-06.
1315
1316  Changes to future timestamps
1317
1318    Volgograd moves from +03 to +04 on 2018-10-28 at 02:00.
1319    (Thanks to Alexander Fetisov and Stepan Golosunov.)
1320
1321    Fiji ends DST 2019-01-13 instead of the 2019-01-20 previously
1322    predicted.  (Thanks to Raymond Kumar.)  Adjust future predictions
1323    accordingly.
1324
1325    Most of Chile will end DST on the first Saturday in April at 24:00 mainland
1326    time, and resume DST on the first Saturday in September at 24:00 mainland
1327    time.  The changes are effective from 2019-04-06, and do not affect the
1328    Magallanes region modeled by America/Punta_Arenas.  (Thanks to Juan Correa
1329    and Tim Parenti.)  Adjust future predictions accordingly.
1330
1331  Changes to past timestamps
1332
1333    The 2018-05-05 North Korea 30-minute time zone change took place
1334    at 23:30 the previous day, not at 00:00 that day.
1335
1336    China's 1988 spring-forward transition was on April 17, not
1337    April 10.  Its DST transitions in 1986/91 were at 02:00, not 00:00.
1338    (Thanks to P Chan.)
1339
1340    Fix several issues for Macau before 1992.  Macau's pre-1904 LMT
1341    was off by 10 s.  Macau switched to +08 in 1904 not 1912, and
1342    temporarily switched to +09/+10 during World War II.  Macau
1343    observed DST in 1942/79, not 1961/80, and there were several
1344    errors for transition times and dates.  (Thanks to P Chan.)
1345
1346    The 1948-1951 fallback transitions in Japan were at 25:00 on
1347    September's second Saturday, not at 24:00.  (Thanks to Phake Nick.)
1348    zic turns this into 01:00 on the day after September's second
1349    Saturday, which is the best that POSIX or C platforms can do.
1350
1351    Incorporate 1940-1949 Asia/Shanghai DST transitions from a 2014
1352    paper by Li Yu, replacing more-questionable data from Shanks.
1353
1354  Changes to time zone abbreviations
1355
1356    Use "PST" and "PDT" for Philippine time.  (Thanks to Paul Goyette.)
1357
1358  Changes to code
1359
1360    zic now always generates TZif files where time type 0 is used for
1361    timestamps before the first transition.  This simplifies the
1362    reading of TZif files and should not affect behavior of existing
1363    TZif readers because the same set of time types is used; only
1364    their internal indexes may have changed.  This affects only the
1365    legacy zones EST5EDT, CST6CDT, MST7MDT, PST8PDT, CET, MET, and
1366    EET, which previously used nonzero types for these timestamps.
1367
1368    Because of the type 0 change, zic no longer outputs a dummy
1369    transition at time -2**59 (before the Big Bang), as clients should
1370    no longer need this to handle historical timestamps correctly.
1371    This reverts a change introduced in 2013d and shrinks most TZif
1372    files by a few bytes.
1373
1374    zic now supports negative time-of-day in Rule and Leap lines, e.g.,
1375    "Rule X min max - Apr lastSun -6:00 1:00 -" means the transition
1376    occurs at 18:00 on the Saturday before the last Sunday in April.
1377    This behavior was documented in 2018a but the code did not
1378    entirely match the documentation.
1379
1380    localtime.c no longer requires at least one time type in TZif
1381    files that lack transitions or have a POSIX-style TZ string.  This
1382    future-proofs the code against possible future extensions to the
1383    format that would allow TZif files with POSIX-style TZ strings and
1384    without transitions or time types.
1385
1386    A read-access subscript error in localtime.c has been fixed.
1387    It could occur only in TZif files with timecnt == 0, something that
1388    does not happen in practice now but could happen in future versions.
1389
1390    localtime.c no longer ignores TZif POSIX-style TZ strings that
1391    specify only standard time.  Instead, these TZ strings now
1392    override the default time type for timestamps after the last
1393    transition (or for all timestamps if there are no transitions),
1394    just as DST strings specifying DST have always done.
1395
1396    leapseconds.awk now outputs "#updated" and "#expires" comments,
1397    and supports leap seconds at the ends of months other than June
1398    and December.  (Inspired by suggestions from Chris Woodbury.)
1399
1400  Changes to documentation
1401
1402    New restrictions: A Rule name must start with a character that
1403    is neither an ASCII digit nor "-" nor "+", and an unquoted name
1404    should not use characters in the set "!$%&'()*,/:;<=>?@[\]^`{|}~".
1405    The latter restriction makes room for future extensions (a
1406    possibility noted by Tom Lane).
1407
1408    tzfile.5 now documents what time types apply before the first and
1409    after the last transition, if any.
1410
1411    Documentation now uses the spelling "timezone" for a TZ setting
1412    that determines timestamp history, and "time zone" for a
1413    geographic region currently sharing the same standard time.
1414
1415    The name "TZif" is now used for the tz binary data format.
1416
1417    tz-link.htm now mentions the A0 TimeZone Migration utilities.
1418    (Thanks to Aldrin Martoq for the link.)
1419
1420  Changes to build procedure
1421
1422    New 'make' target 'rearguard_tarballs' to build the rearguard
1423    tarball only.  This is a convenience on platforms that lack lzip
1424    if you want to build the rearguard tarball.  (Problem reported by
1425    Deborah Goldsmith.)
1426
1427    tzdata.zi is now more stable from release to release.  (Problem
1428    noted by Tom Lane.)  It is also a bit shorter.
1429
1430    tzdata.zi now can contain comment lines documenting configuration
1431    information, such as which data format was selected, which input
1432    files were used, and how leap seconds are treated.  (Problems
1433    noted by Lester Caine and Brian Inglis.)  If the Makefile defaults
1434    are used these comment lines are absent, for backward
1435    compatibility.  A redistributor intending to alter its copy of the
1436    files should also append "-LABEL" to the 'version' file's first
1437    line, where "LABEL" identifies the redistributor's change.
1438
1439
1440Release 2018e - 2018-05-01 23:42:51 -0700
1441
1442  Briefly:
1443
1444    North Korea switches back to +09 on 2018-05-05.
1445    The main format uses negative DST again, for Ireland etc.
1446    'make tarballs' now also builds a rearguard tarball.
1447    New 's' and 'd' suffixes in SAVE columns of Rule and Zone lines.
1448
1449  Changes to past and future timestamps
1450
1451    North Korea switches back from +0830 to +09 on 2018-05-05.
1452    (Thanks to Kang Seonghoon, Arthur David Olson, Seo Sanghyeon,
1453    and Tim Parenti.)
1454
1455    Bring back the negative-DST changes of 2018a, except be more
1456    compatible with data parsers that do not support negative DST.
1457    Also, this now affects historical timestamps in Namibia and the
1458    former Czechoslovakia, not just Ireland.  The main format now uses
1459    negative DST to model timestamps in Europe/Dublin (from 1971 on),
1460    Europe/Prague (1946/7), and Africa/Windhoek (1994/2017).  This
1461    does not affect UT offsets, only time zone abbreviations and the
1462    tm_isdst flag.  Also, this does not affect rearguard or vanguard
1463    formats; effectively the main format now uses vanguard instead of
1464    rearguard format.  Data parsers that do not support negative DST
1465    can still use data from the rearguard tarball described below.
1466
1467  Changes to build procedure
1468
1469    The command 'make tarballs' now also builds the tarball
1470    tzdataVERSION-rearguard.tar.gz, which is like tzdataVERSION.tar.gz
1471    except that it uses rearguard format intended for trailing-edge
1472    data parsers.
1473
1474  Changes to data format and to code
1475
1476    The SAVE column of Rule and Zone lines can now have an 's' or 'd'
1477    suffix, which specifies whether the adjusted time is standard time
1478    or daylight saving time.  If no suffix is given, daylight saving
1479    time is used if and only if the SAVE column is nonzero; this is
1480    the longstanding behavior.  Although this new feature is not used
1481    in tzdata, it could be used to specify the legal time in Namibia
1482    1994-2017, as opposed to the popular time (see below).
1483
1484  Changes to past timestamps
1485
1486    From 1994 through 2017 Namibia observed DST in winter, not summer.
1487    That is, it used negative DST, as Ireland still does.  This change
1488    does not affect UTC offsets; it affects only the tm_isdst flag and
1489    the abbreviation used during summer, which is now CAT, not WAST.
1490    Although (as noted by Michael Deckers) summer and winter time were
1491    both simply called "standard time" in Namibian law, in common
1492    practice winter time was considered to be DST (as noted by Stephen
1493    Colebourne).  The full effect of this change is only in vanguard
1494    and main format; in rearguard format, the tm_isdst flag is still
1495    zero in winter and nonzero in summer.
1496
1497    In 1946/7 Czechoslovakia also observed negative DST in winter.
1498    The full effect of this change is only in vanguard and main
1499    formats; in rearguard format, it is modeled as plain GMT without
1500    daylight saving.  Also, the dates of some 1944/5 DST transitions
1501    in Czechoslovakia have been changed.
1502
1503
1504Release 2018d - 2018-03-22 07:05:46 -0700
1505
1506  Briefly:
1507
1508  Palestine starts DST a week earlier in 2018.
1509  Add support for vanguard and rearguard data consumers.
1510  Add subsecond precision to source data format, though not to data.
1511
1512  Changes to future timestamps
1513
1514    In 2018, Palestine starts DST on March 24, not March 31.
1515    Adjust future predictions accordingly.  (Thanks to Sharef Mustafa.)
1516
1517  Changes to past and future timestamps
1518
1519    Casey Station in Antarctica changed from +11 to +08 on 2018-03-11
1520    at 04:00.  (Thanks to Steffen Thorsen.)
1521
1522  Changes to past timestamps
1523
1524    Historical transitions for Uruguay, represented by
1525    America/Montevideo, have been updated per official legal documents,
1526    replacing previous data mainly originating from the inventions of
1527    Shanks & Pottenger.  This has resulted in adjustments ranging from
1528    30 to 90 minutes in either direction over at least two dozen
1529    distinct periods ranging from one day to several years in length.
1530    A mere handful of pre-1991 transitions are unaffected; data since
1531    then has come from more reliable contemporaneous reporting.  These
1532    changes affect various timestamps in 1920-1923, 1936, 1939,
1533    1942-1943, 1959, 1966-1970, 1972, 1974-1980, and 1988-1990.
1534    Additionally, Uruguay's pre-standard-time UT offset has been
1535    adjusted westward by 7 seconds, from UT-03:44:44 to UT-03:44:51, to
1536    match the location of the Observatory of the National Meteorological
1537    Institute in Montevideo.
1538    (Thanks to Jeremie Bonjour, Tim Parenti, and Michael Deckers.)
1539
1540    East Kiribati skipped New Year's Eve 1994, not New Year's Day 1995.
1541    (Thanks to Kerry Shetline.)
1542
1543    Fix the 1912-01-01 transition for Portugal and its colonies.
1544    This transition was at 00:00 according to the new UT offset, not
1545    according to the old one.  Also assume that Cape Verde switched on
1546    the same date as the rest, not in 1907.  This affects
1547    Africa/Bissau, Africa/Sao_Tome, Asia/Macau, Atlantic/Azores,
1548    Atlantic/Cape_Verde, Atlantic/Madeira, and Europe/Lisbon.
1549    (Thanks to Michael Deckers.)
1550
1551    Fix an off-by-1 error for pre-1913 timestamps in Jamaica and in
1552    Turks & Caicos.
1553
1554  Changes to past time zone abbreviations
1555
1556    MMT took effect in Uruguay from 1908-06-10, not 1898-06-28.  There
1557    is no clock change associated with the transition.
1558
1559  Changes to build procedure
1560
1561    The new DATAFORM macro in the Makefile lets the installer choose
1562    among three source data formats.  The idea is to lessen downstream
1563    disruption when data formats are improved.
1564
1565    * DATAFORM=vanguard installs from the latest, bleeding-edge
1566      format.  DATAFORM=main (the default) installs from the format
1567      used in the 'africa' etc. files.  DATAFORM=rearguard installs
1568      from a trailing-edge format.  Eventually, elements of today's
1569      vanguard format should move to the main format, and similarly
1570      the main format's features should eventually move to the
1571      rearguard format.
1572
1573    * In the current version, the main and rearguard formats are
1574      identical and match that of 2018c, so this change does not
1575      affect default behavior.  The vanguard format currently contains
1576      one feature not in the main format: negative SAVE values.  This
1577      improves support for Ireland, which uses Irish Standard Time
1578      (IST, UTC+01) in summer and GMT (UTC) in winter.  tzcode has
1579      supported negative SAVE values for decades, and this feature
1580      should move to the main format soon.  However, it will not move
1581      to the rearguard format for quite some time because some
1582      downstream parsers do not support it.
1583
1584    * The build procedure constructs three files vanguard.zi, main.zi,
1585      and rearguard.zi, one for each format.  Although the files
1586      represent essentially the same data, they may have minor
1587      discrepancies that users are not likely to notice.  The files
1588      are intended for downstream data consumers and are not
1589      installed.  Zoneinfo parsers that do not support negative SAVE values
1590      should start using rearguard.zi, so that they will be unaffected
1591      when the negative-DST feature moves from vanguard to main.
1592      Bleeding-edge Zoneinfo parsers that support the new features
1593      already can use vanguard.zi; in this respect, current tzcode is
1594      bleeding-edge.
1595
1596    The Makefile should now be safe for parallelized builds, and 'make
1597    -j to2050new.tzs' is now much faster on a multiprocessor host
1598    with GNU Make.
1599
1600    When built with -DSUPPRESS_TZDIR, the tzcode library no longer
1601    prepends TZDIR/ to file names that do not begin with '/'.  This is
1602    not recommended for general use, due to its security implications.
1603    (From a suggestion by Manuela Friedrich.)
1604
1605  Changes to code
1606
1607    zic now accepts subsecond precision in expressions like
1608    00:19:32.13, which is approximately the legal time of the
1609    Netherlands from 1835 to 1937.  However, because it is
1610    questionable whether the few recorded uses of non-integer offsets
1611    had subsecond precision in practice, there are no plans for tzdata
1612    to use this feature.  (Thanks to Steve Allen for pointing out
1613    the limitations of historical data in this area.)
1614
1615    The code is a bit more portable to MS-Windows.  Installers can
1616    compile with -DRESERVE_STD_EXT_IDS on MS-Windows platforms that
1617    reserve identifiers like 'localtime'.  (Thanks to Manuela
1618    Friedrich.)
1619
1620  Changes to documentation and commentary
1621
1622    theory.html now outlines tzdb's extensions to POSIX's model for
1623    civil time, and has a section "POSIX features no longer needed"
1624    that lists POSIX API components that are now vestigial.
1625    (From suggestions by Steve Summit.)  It also better distinguishes
1626    time zones from tz regions.  (From a suggestion by Guy Harris.)
1627
1628    Commentary is now more consistent about using the phrase "daylight
1629    saving time", to match the C name tm_isdst.  Daylight saving time
1630    need not occur in summer, and need not have a positive offset from
1631    standard time.
1632
1633    Commentary about historical transitions in Uruguay has been expanded
1634    with links to many relevant legal documents.
1635    (Thanks to Tim Parenti.)
1636
1637    Commentary now uses some non-ASCII characters with Unicode value
1638    less than U+0100, as they can be useful and should work even with
1639    older editors such as XEmacs.
1640
1641
1642Release 2018c - 2018-01-22 23:00:44 -0800
1643
1644  Briefly:
1645  Revert Irish changes that relied on negative SAVE values.
1646
1647  Changes to tm_isdst
1648
1649    Revert the 2018a change to Europe/Dublin.  As before, this change
1650    does not affect UT offsets or abbreviations; it affects only
1651    whether timestamps are considered to be standard time or
1652    daylight-saving time, as expressed in the tm_isdst flag of C's
1653    struct tm type.  This reversion is intended to be a temporary
1654    workaround for problems discovered with downstream uses of
1655    releases 2018a and 2018b, which implemented Irish time by using
1656    negative SAVE values in the Eire rules of the 'europe' file.
1657    Although negative SAVE values have been part of tzcode for many
1658    years and are supported by many platforms, they were not
1659    documented before 2018a and ICU and OpenJDK do not currently
1660    support them.  A mechanism to export data to platforms lacking
1661    support for negative DST is planned to be developed before the
1662    change is reapplied.  (Problems reported by Deborah Goldsmith and
1663    Stephen Colebourne.)
1664
1665  Changes to past timestamps
1666
1667    Japanese DST transitions (1948-1951) were Sundays at 00:00, not
1668    Saturdays or Sundays at 02:00.  (Thanks to Takayuki Nikai.)
1669
1670  Changes to build procedure
1671
1672    The build procedure now works around mawk 1.3.3's lack of support
1673    for character class expressions.  (Problem reported by Ohyama.)
1674
1675
1676Release 2018b - 2018-01-17 23:24:48 -0800
1677
1678  Briefly:
1679  Fix a packaging problem in tz2018a, which was missing 'pacificnew'.
1680
1681  Changes to build procedure
1682
1683    The distribution now contains the file 'pacificnew' again.
1684    This file was inadvertently omitted in the 2018a distribution.
1685    (Problem reported by Matias Fonzo.)
1686
1687
1688Release 2018a - 2018-01-12 22:29:21 -0800
1689
1690  Briefly:
1691  São Tomé and Príncipe switched from +00 to +01.
1692  Brazil's DST will now start on November's first Sunday.
1693  Ireland's standard time is now in the summer, not the winter.
1694  Use Debian-style installation locations, instead of 4.3BSD-style.
1695  New zic option -t.
1696
1697  Changes to past and future timestamps
1698
1699    São Tomé and Príncipe switched from +00 to +01 on 2018-01-01 at
1700    01:00.  (Thanks to Steffen Thorsen and Michael Deckers.)
1701
1702  Changes to future timestamps
1703
1704    Starting in 2018 southern Brazil will begin DST on November's
1705    first Sunday instead of October's third Sunday.  (Thanks to
1706    Steffen Thorsen.)
1707
1708  Changes to past timestamps
1709
1710    A discrepancy of 4 s in timestamps before 1931 in South Sudan has
1711    been corrected.  The 'backzone' and 'zone.tab' files did not agree
1712    with the 'africa' and 'zone1970.tab' files.  (Problem reported by
1713    Michael Deckers.)
1714
1715    The abbreviation invented for Bolivia Summer Time (1931-2) is now
1716    BST instead of BOST, to be more consistent with the convention
1717    used for Latvian Summer Time (1918-9) and for British Summer Time.
1718
1719  Changes to tm_isdst
1720
1721    Change Europe/Dublin so that it observes Irish Standard Time (UT
1722    +01) in summer and GMT (as negative daylight-saving) in winter,
1723    instead of observing standard time (GMT) in winter and Irish
1724    Summer Time (UT +01) in summer.  This change does not affect UT
1725    offsets or abbreviations; it affects only whether timestamps are
1726    considered to be standard time or daylight-saving time, as
1727    expressed in the tm_isdst flag of C's struct tm type.
1728    (Discrepancy noted by Derick Rethans.)
1729
1730  Changes to build procedure
1731
1732    The default installation locations have been changed to mostly
1733    match Debian circa 2017, instead of being designed as an add-on to
1734    4.3BSD circa 1986.  This affects the Makefile macros TOPDIR,
1735    TZDIR, MANDIR, and LIBDIR.  New Makefile macros TZDEFAULT, USRDIR,
1736    USRSHAREDIR, BINDIR, ZDUMPDIR, and ZICDIR let installers tailor
1737    locations more precisely.  (This responds to suggestions from
1738    Brian Inglis and from Steve Summit.)
1739
1740    The default installation procedure no longer creates the
1741    backward-compatibility link US/Pacific-New, which causes
1742    confusion during user setup (e.g., see Debian bug 815200).
1743    Use 'make BACKWARD="backward pacificnew"' to create the link
1744    anyway, for now.  Eventually we plan to remove the link entirely.
1745
1746    tzdata.zi now contains a version-number comment.
1747    (Suggested by Tom Lane.)
1748
1749    The Makefile now quotes values like BACKWARD more carefully when
1750    passing them to the shell.  (Problem reported by Zefram.)
1751
1752    Builders no longer need to specify -DHAVE_SNPRINTF on platforms
1753    that have snprintf and use pre-C99 compilers.  (Problem reported
1754    by Jon Skeet.)
1755
1756  Changes to code
1757
1758    zic has a new option -t FILE that specifies the location of the
1759    file that determines local time when TZ is unset.  The default for
1760    this location can be configured via the new TZDEFAULT makefile
1761    macro, which defaults to /etc/localtime.
1762
1763    Diagnostics and commentary now distinguish UT from UTC more
1764    carefully; see theory.html for more information about UT vs UTC.
1765
1766    zic has been ported to GCC 8's -Wstringop-truncation option.
1767    (Problem reported by Martin Sebor.)
1768
1769  Changes to documentation and commentary
1770
1771    The zic man page now documents the longstanding behavior that
1772    times and years can be out of the usual range, with negative times
1773    counting backwards from midnight and with year 0 preceding year 1.
1774    (Problem reported by Michael Deckers.)
1775
1776    The theory.html file now mentions the POSIX limit of six chars
1777    per abbreviation, and lists alphabetic abbreviations used.
1778
1779    The files tz-art.htm and tz-link.htm have been renamed to
1780    tz-art.html and tz-link.html, respectively, for consistency with
1781    other file names and to simplify web server configuration.
1782
1783
1784Release 2017c - 2017-10-20 14:49:34 -0700
1785
1786  Briefly:
1787  Northern Cyprus switches from +03 to +02/+03 on 2017-10-29.
1788  Fiji ends DST 2018-01-14, not 2018-01-21.
1789  Namibia switches from +01/+02 to +02 on 2018-04-01.
1790  Sudan switches from +03 to +02 on 2017-11-01.
1791  Tonga likely switches from +13/+14 to +13 on 2017-11-05.
1792  Turks & Caicos switches from -04 to -05/-04 on 2018-11-04.
1793  A new file tzdata.zi now holds a small text copy of all data.
1794  The zic input format has been regularized slightly.
1795
1796  Changes to future timestamps
1797
1798    Northern Cyprus has decided to resume EU rules starting
1799    2017-10-29, thus reinstituting winter time.
1800
1801    Fiji ends DST 2018-01-14 instead of the 2018-01-21 previously
1802    predicted.  (Thanks to Dominic Fok.)  Adjust future predictions
1803    accordingly.
1804
1805    Namibia will switch from +01 with DST to +02 all year on
1806    2017-09-03 at 02:00.  This affects UT offsets starting 2018-04-01
1807    at 02:00.  (Thanks to Steffen Thorsen.)
1808
1809    Sudan will switch from +03 to +02 on 2017-11-01.  (Thanks to Ahmed
1810    Atyya and Yahia Abdalla.)  South Sudan is not switching, so
1811    Africa/Juba is no longer a link to Africa/Khartoum.
1812
1813    Tonga has likely ended its experiment with DST, and will not
1814    adjust its clocks on 2017-11-05.  Although Tonga has not announced
1815    whether it will continue to observe DST, the IATA is assuming that
1816    it will not.  (Thanks to David Wade.)
1817
1818    Turks & Caicos will switch from -04 all year to -05 with US DST on
1819    2018-03-11 at 03:00.  This affects UT offsets starting 2018-11-04
1820    at 02:00.  (Thanks to Steffen Thorsen.)
1821
1822  Changes to past timestamps
1823
1824    Namibia switched from +02 to +01 on 1994-03-21, not 1994-04-03.
1825    (Thanks to Arthur David Olson.)
1826
1827    Detroit did not observe DST in 1967.
1828
1829    Use railway time for Asia/Kolkata before 1941, by switching to
1830    Madras local time (UT +052110) in 1870, then to IST (UT +0530) in
1831    1906.  Also, treat 1941-2's +0630 as DST, like 1942-5.
1832
1833    Europe/Dublin's 1946 and 1947 fallback transitions occurred at
1834    02:00 standard time, not 02:00 DST.  (Thanks to Michael Deckers.)
1835
1836    Pacific/Apia and Pacific/Pago_Pago switched from Antipodean to
1837    American time in 1892, not 1879.  (Thanks to Michael Deckers.)
1838
1839    Adjust the 1867 transition in Alaska to better reflect the
1840    historical record, by changing it to occur on 1867-10-18 at 15:30
1841    Sitka time rather than at the start of 1867-10-17 local time.
1842    Although strictly speaking this is accurate only for Sitka,
1843    the rest of Alaska's blanks need to be filled in somehow.
1844
1845    Fix off-by-one errors in UT offsets for Adak and Nome before 1867.
1846    (Thanks to Michael Deckers.)
1847
1848    Add 7 s to the UT offset in Asia/Yangon before 1920.
1849
1850  Changes to zone names
1851
1852    Remove Canada/East-Saskatchewan from the 'backward' file, as it
1853    exceeded the 14-character limit and was an unused misnomer anyway.
1854
1855  Changes to build procedure
1856
1857    To support applications that prefer to read time zone data in text
1858    form, two zic input files tzdata.zi and leapseconds are now
1859    installed by default.  The commands 'zic tzdata.zi' and 'zic -L
1860    leapseconds tzdata.zi' can reproduce the tzdata binary files
1861    without and with leap seconds, respectively.  To prevent these two
1862    new files from being installed, use 'make TZDATA_TEXT=', and to
1863    suppress leap seconds from the tzdata text installation, use 'make
1864    TZDATA_TEXT=tzdata.zi'.
1865
1866    'make BACKWARD=' now suppresses backward-compatibility names
1867    like 'US/Pacific' that are defined in the 'backward' and
1868    'pacificnew' files.
1869
1870    'make check' now works on systems that lack a UTF-8 locale,
1871    or that lack the nsgmls program.  Set UTF8_LOCALE to configure
1872    the name of a UTF-8 locale, if you have one.
1873
1874    Y2K runtime checks are no longer enabled by default.  Add
1875    -DDEPRECATE_TWO_DIGIT_YEARS to CFLAGS to enable them, instead of
1876    adding -DNO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
1877    to disable them.  (New name suggested by Brian Inglis.)
1878
1879    The build procedure for zdump now works on AIX 7.1.
1880    (Problem reported by Kees Dekker.)
1881
1882  Changes to code
1883
1884    zic and the reference runtime now reject multiple leap seconds
1885    within 28 days of each other, or leap seconds before the Epoch.
1886    As a result, support for double leap seconds, which was
1887    obsolescent and undocumented, has been removed.  Double leap
1888    seconds were an error in the C89 standard; they have never existed
1889    in civil timekeeping.  (Thanks to Robert Elz and Bradley White for
1890    noticing glitches in the code that uncovered this problem.)
1891
1892    zic now warns about use of the obsolescent and undocumented -y
1893    option, and about use of the obsolescent TYPE field of Rule lines.
1894
1895    zic now allows unambiguous abbreviations like "Sa" and "Su" for
1896    weekdays; formerly it rejected them due to a bug.  Conversely, zic
1897    no longer considers non-prefixes to be abbreviations; for example,
1898    it no longer accepts "lF" as an abbreviation for "lastFriday".
1899    Also, zic warns about the undocumented usage with a "last-"
1900    prefix, e.g., "last-Fri".
1901
1902    Similarly, zic now accepts the unambiguous abbreviation "L" for
1903    "Link" in ordinary context and for "Leap" in leap-second context.
1904    Conversely, zic no longer accepts non-prefixes such as "La" as
1905    abbreviations for words like "Leap".
1906
1907    zic no longer accepts leap second lines in ordinary input, or
1908    ordinary lines in leap second input.  Formerly, zic sometimes
1909    warned about this undocumented usage and handled it incorrectly.
1910
1911    The new macro HAVE_TZNAME governs whether the tzname external
1912    variable is exported, instead of USG_COMPAT.  USG_COMPAT now
1913    governs only the external variables "timezone" and "daylight".
1914    This change is needed because the three variables are not in the
1915    same category: although POSIX requires tzname, it specifies the
1916    other two variables as optional.  Also, USG_COMPAT is now 1 or 0:
1917    if not defined, the code attempts to guess it from other macros.
1918
1919    localtime.c and difftime.c no longer require stdio.h, and .c files
1920    other than zic.c no longer require sys/wait.h.
1921
1922    zdump.c no longer assumes snprintf.  (Reported by Jonathan Leffler.)
1923
1924    Calculation of time_t extrema works around a bug in GCC 4.8.4
1925    (Reported by Stan Shebs and Joseph Myers.)
1926
1927    zic.c no longer mistranslates formats of line numbers in non-English
1928    locales.  (Problem reported by Benno Schulenberg.)
1929
1930    Several minor changes have been made to the code to make it a
1931    bit easier to port to MS-Windows and Solaris.  (Thanks to Kees
1932    Dekker for reporting the problems.)
1933
1934  Changes to documentation and commentary
1935
1936    The two new files 'theory.html' and 'calendars' contain the
1937    contents of the removed file 'Theory'.  The goal is to document
1938    tzdb theory more accessibly.
1939
1940    The zic man page now documents abbreviation rules.
1941
1942    tz-link.htm now covers how to apply tzdata changes to clients.
1943    (Thanks to Jorge Fábregas for the AIX link.)  It also mentions MySQL.
1944
1945    The leap-seconds.list URL has been updated to something that is
1946    more reliable for tzdb.  (Thanks to Tim Parenti and Brian Inglis.)
1947
1948Release 2017b - 2017-03-17 07:30:38 -0700
1949
1950  Briefly: Haiti has resumed DST.
1951
1952  Changes to past and future timestamps
1953
1954    Haiti resumed observance of DST in 2017.  (Thanks to Steffen Thorsen.)
1955
1956  Changes to past timestamps
1957
1958    Liberia changed from -004430 to +00 on 1972-01-07, not 1972-05-01.
1959
1960    Use "MMT" to abbreviate Liberia's time zone before 1972, as "-004430"
1961    is one byte over the POSIX limit.  (Problem reported by Derick Rethans.)
1962
1963  Changes to code
1964
1965    The reference localtime implementation now falls back on the
1966    current US daylight-saving transition rules rather than the
1967    1987-2006 rules.  This fallback occurs only when (1) the TZ
1968    environment variable has a value like "AST4ADT" that asks
1969    for daylight saving time but does not specify the rules, (2) there
1970    is no file by that name, and (3) the TZDEFRULES file cannot be
1971    loaded.  (Thanks to Tom Lane.)
1972
1973
1974Release 2017a - 2017-02-28 00:05:36 -0800
1975
1976  Briefly: Southern Chile moves from -04/-03 to -03, and Mongolia
1977  discontinues DST.
1978
1979  Changes to future timestamps
1980
1981    Mongolia no longer observes DST.  (Thanks to Ganbold Tsagaankhuu.)
1982
1983    Chile's Region of Magallanes moves from -04/-03 to -03 year-round.
1984    Its clocks diverge from America/Santiago starting 2017-05-13 at
1985    23:00, hiving off a new zone America/Punta_Arenas.  Although the
1986    Chilean government says this change expires in May 2019, for now
1987    assume it's permanent.  (Thanks to Juan Correa and Deborah
1988    Goldsmith.)  This also affects Antarctica/Palmer.
1989
1990  Changes to past timestamps
1991
1992    Fix many entries for historical timestamps for Europe/Madrid
1993    before 1979, to agree with tables compiled by Pere Planesas of the
1994    National Astronomical Observatory of Spain.  As a side effect,
1995    this changes some timestamps for Africa/Ceuta before 1929, which
1996    are probably guesswork anyway.  (Thanks to Steve Allen and
1997    Pierpaolo Bernardi for the heads-ups, and to Michael Deckers for
1998    correcting the 1901 transition.)
1999
2000    Ecuador observed DST from 1992-11-28 to 1993-02-05.
2001    (Thanks to Alois Treindl.)
2002
2003    Asia/Atyrau and Asia/Oral were at +03 (not +04) before 1930-06-21.
2004    (Thanks to Stepan Golosunov.)
2005
2006  Changes to past and future time zone abbreviations
2007
2008    Switch to numeric time zone abbreviations for South America, as
2009    part of the ongoing project of removing invented abbreviations.
2010    This avoids the need to invent an abbreviation for the new Chilean
2011    new zone.  Similarly, switch from invented to numeric time zone
2012    abbreviations for Afghanistan, American Samoa, the Azores,
2013    Bangladesh, Bhutan, the British Indian Ocean Territory, Brunei,
2014    Cape Verde, Chatham Is, Christmas I, Cocos (Keeling) Is, Cook Is,
2015    Dubai, East Timor, Eucla, Fiji, French Polynesia, Greenland,
2016    Indochina, Iran, Iraq, Kiribati, Lord Howe, Macquarie, Malaysia,
2017    the Maldives, Marshall Is, Mauritius, Micronesia, Mongolia,
2018    Myanmar, Nauru, Nepal, New Caledonia, Niue, Norfolk I, Palau,
2019    Papua New Guinea, the Philippines, Pitcairn, Qatar, Réunion, St
2020    Pierre & Miquelon, Samoa, Saudi Arabia, Seychelles, Singapore,
2021    Solomon Is, Tokelau, Tuvalu, Wake, Vanuatu, Wallis & Futuna, and
2022    Xinjiang; for 20-minute daylight saving time in Ghana before 1943;
2023    for half-hour daylight saving time in Belize before 1944 and in
2024    the Dominican Republic before 1975; and for Canary Islands before
2025    1946, for Guinea-Bissau before 1975, for Iceland before 1969, for
2026    Indian Summer Time before 1942, for Indonesia before around 1964,
2027    for Kenya before 1960, for Liberia before 1973, for Madeira before
2028    1967, for Namibia before 1943, for the Netherlands in 1937-9, for
2029    Pakistan before 1971, for Western Sahara before 1977, and for
2030    Zaporozhye in 1880-1924.
2031
2032    For Alaska time from 1900 through 1967, instead of "CAT" use the
2033    abbreviation "AST", the abbreviation commonly used at the time
2034    (Atlantic Standard Time had not been standardized yet).  Use "AWT"
2035    and "APT" instead of the invented abbreviations "CAWT" and "CAPT".
2036
2037    Use "CST" and "CDT" instead of invented abbreviations for Macau
2038    before 1999 and Taiwan before 1938, and use "JST" instead of the
2039    invented abbreviation "JCST" for Japan and Korea before 1938.
2040
2041  Change to database entry category
2042
2043    Move the Pacific/Johnston link from 'australasia' to 'backward',
2044    since Johnston is now uninhabited.
2045
2046  Changes to code
2047
2048    zic no longer mishandles some transitions in January 2038 when it
2049    attempts to work around Qt bug 53071.  This fixes a bug affecting
2050    Pacific/Tongatapu that was introduced in zic 2016e.  localtime.c
2051    now contains a workaround, useful when loading a file generated by
2052    a buggy zic.  (Problem and localtime.c fix reported by Bradley
2053    White.)
2054
2055    zdump -i now outputs non-hour numeric time zone abbreviations
2056    without a colon, e.g., "+0530" rather than "+05:30".  This agrees
2057    with zic %z and with common practice, and simplifies auditing of
2058    zdump output.
2059
2060    zdump is now buildable again with -DUSE_LTZ=0.
2061    (Problem reported by Joseph Myers.)
2062
2063    zdump.c now always includes private.h, to avoid code duplication
2064    with private.h.  (Problem reported by Kees Dekker.)
2065
2066    localtime.c no longer mishandles early or late timestamps
2067    when TZ is set to a POSIX-style string that specifies DST.
2068    (Problem reported by Kees Dekker.)
2069
2070    date and strftime now cause %z to generate "-0000" instead of
2071    "+0000" when the UT offset is zero and the time zone abbreviation
2072    begins with "-".
2073
2074  Changes to documentation and commentary
2075
2076    The 'Theory' file now better documents choice of historical time
2077    zone abbreviations.  (Problems reported by Michael Deckers.)
2078
2079    tz-link.htm now covers leap smearing, which is popular in clouds.
2080
2081
2082Release 2016j - 2016-11-22 23:17:13 -0800
2083
2084  Briefly: Saratov, Russia moves from +03 to +04 on 2016-12-04.
2085
2086  Changes to future timestamps
2087
2088    Saratov, Russia switches from +03 to +04 on 2016-12-04 at 02:00.
2089    This hives off a new zone Europe/Saratov from Europe/Volgograd.
2090    (Thanks to Yuri Konotopov and Stepan Golosunov.)
2091
2092  Changes to past timestamps
2093
2094    The new zone Asia/Atyrau for Atyraū Region, Kazakhstan, is like
2095    Asia/Aqtau except it switched from +05/+06 to +04/+05 in spring
2096    1999, not fall 1994.  (Thanks to Stepan Golosunov.)
2097
2098  Changes to past time zone abbreviations
2099
2100    Asia/Gaza and Asia/Hebron now use "EEST", not "EET", to denote
2101    summer time before 1948.  The old use of "EET" was a typo.
2102
2103  Changes to code
2104
2105    zic no longer mishandles file systems that lack hard links, fixing
2106    bugs introduced in 2016g.  (Problems reported by Tom Lane.)
2107    Also, when the destination already contains symbolic links, zic
2108    should now work better on systems where the 'link' system call
2109    does not follow symbolic links.
2110
2111  Changes to documentation and commentary
2112
2113    tz-link.htm now documents the relationship between release version
2114    numbers and development-repository commit tags.  (Suggested by
2115    Paul Koning.)
2116
2117    The 'Theory' file now documents UT.
2118
2119    iso3166.tab now accents "Curaçao", and commentary now mentions
2120    the names "Cabo Verde" and "Czechia".  (Thanks to Jiří Boháč.)
2121
2122
2123Release 2016i - 2016-11-01 23:19:52 -0700
2124
2125  Briefly: Cyprus split into two time zones on 2016-10-30, and Tonga
2126  reintroduces DST on 2016-11-06.
2127
2128  Changes to future timestamps
2129
2130    Pacific/Tongatapu begins DST on 2016-11-06 at 02:00, ending on
2131    2017-01-15 at 03:00.  Assume future observances in Tonga will be
2132    from the first Sunday in November through the third Sunday in
2133    January, like Fiji.  (Thanks to Pulu ʻAnau.)  Switch to numeric
2134    time zone abbreviations for this zone.
2135
2136  Changes to past and future timestamps
2137
2138    Northern Cyprus is now +03 year round, causing a split in Cyprus
2139    time zones starting 2016-10-30 at 04:00.  This creates a zone
2140    Asia/Famagusta.  (Thanks to Even Scharning and Matt Johnson.)
2141
2142    Antarctica/Casey switched from +08 to +11 on 2016-10-22.
2143    (Thanks to Steffen Thorsen.)
2144
2145  Changes to past timestamps
2146
2147    Several corrections were made for pre-1975 timestamps in Italy.
2148    These affect Europe/Malta, Europe/Rome, Europe/San_Marino, and
2149    Europe/Vatican.
2150
2151    First, the 1893-11-01 00:00 transition in Italy used the new UT
2152    offset (+01), not the old (+00:49:56).  (Thanks to Michael
2153    Deckers.)
2154
2155    Second, rules for daylight saving in Italy were changed to agree
2156    with Italy's National Institute of Metrological Research (INRiM)
2157    except for 1944, as follows (thanks to Pierpaolo Bernardi, Brian
2158    Inglis, and Michael Deckers):
2159
2160      The 1916-06-03 transition was at 24:00, not 00:00.
2161
2162      The 1916-10-01, 1919-10-05, and 1920-09-19 transitions were at
2163      00:00, not 01:00.
2164
2165      The 1917-09-30 and 1918-10-06 transitions were at 24:00, not
2166      01:00.
2167
2168      The 1944-09-17 transition was at 03:00, not 01:00.  This
2169      particular change is taken from Italian law as INRiM's table,
2170      (which says 02:00) appears to have a typo here.  Also, keep the
2171      1944-04-03 transition for Europe/Rome, as Rome was controlled by
2172      Germany then.
2173
2174      The 1967-1970 and 1972-1974 fallback transitions were at 01:00,
2175      not 00:00.
2176
2177  Changes to code
2178
2179    The code should now be buildable on AmigaOS merely by setting the
2180    appropriate Makefile variables.  (From a patch by Carsten Larsen.)
2181
2182
2183Release 2016h - 2016-10-19 23:17:57 -0700
2184
2185  Changes to future timestamps
2186
2187    Asia/Gaza and Asia/Hebron end DST on 2016-10-29 at 01:00, not
2188    2016-10-21 at 00:00.  (Thanks to Sharef Mustafa.)  Predict that
2189    future fall transitions will be on the last Saturday of October
2190    at 01:00, which is consistent with predicted spring transitions
2191    on the last Saturday of March.  (Thanks to Tim Parenti.)
2192
2193  Changes to past timestamps
2194
2195    In Turkey, transitions in 1986-1990 were at 01:00 standard time
2196    not at 02:00, and the spring 1994 transition was on March 20, not
2197    March 27.  (Thanks to Kıvanç Yazan.)
2198
2199  Changes to past and future time zone abbreviations
2200
2201    Asia/Colombo now uses numeric time zone abbreviations like "+0530"
2202    instead of alphabetic ones like "IST" and "LKT".  Various
2203    English-language sources use "IST", "LKT" and "SLST", with no
2204    working consensus.  (Usage of "SLST" mentioned by Sadika
2205    Sumanapala.)
2206
2207  Changes to code
2208
2209    zic no longer mishandles relativizing file names when creating
2210    symbolic links like /etc/localtime, when these symbolic links
2211    are outside the usual directory hierarchy.  This fixes a bug
2212    introduced in 2016g.  (Problem reported by Andreas Stieger.)
2213
2214  Changes to build procedure
2215
2216    New rules 'traditional_tarballs' and 'traditional_signatures' for
2217    building just the traditional-format distribution.  (Requested by
2218    Deborah Goldsmith.)
2219
2220    The file 'version' is now put into the tzdata tarball too.
2221    (Requested by Howard Hinnant.)
2222
2223  Changes to documentation and commentary
2224
2225    The 'Theory' file now has a section on interface stability.
2226    (Requested by Paul Koning.)  It also mentions features like
2227    tm_zone and localtime_rz that have long been supported by the
2228    reference code.
2229
2230    tz-link.htm has improved coverage of time zone boundaries suitable
2231    for geolocation.  (Thanks to heads-ups from Evan Siroky and Matt
2232    Johnson.)
2233
2234    The US commentary now mentions Allen and the "day of two noons".
2235
2236    The Fiji commentary mentions the government's 2016-10-03 press
2237    release.  (Thanks to Raymond Kumar.)
2238
2239
2240Release 2016g - 2016-09-13 08:56:38 -0700
2241
2242  Changes to future timestamps
2243
2244    Turkey switched from EET/EEST (+02/+03) to permanent +03,
2245    effective 2016-09-07.  (Thanks to Burak AYDIN.)  Use "+03" rather
2246    than an invented abbreviation for the new time.
2247
2248    New leap second 2016-12-31 23:59:60 UTC as per IERS Bulletin C 52.
2249    (Thanks to Tim Parenti.)
2250
2251  Changes to past timestamps
2252
2253    For America/Los_Angeles, spring-forward transition times have been
2254    corrected from 02:00 to 02:01 in 1948, and from 02:00 to 01:00 in
2255    1950-1966.
2256
2257    For zones using Soviet time on 1919-07-01, transitions to UT-based
2258    time were at 00:00 UT, not at 02:00 local time.  The affected
2259    zones are Europe/Kirov, Europe/Moscow, Europe/Samara, and
2260    Europe/Ulyanovsk.  (Thanks to Alexander Belopolsky.)
2261
2262  Changes to past and future time zone abbreviations
2263
2264    The Factory zone now uses the time zone abbreviation -00 instead
2265    of a long English-language string, as -00 is now the normal way to
2266    represent an undefined time zone.
2267
2268    Several zones in Antarctica and the former Soviet Union, along
2269    with zones intended for ships at sea that cannot use POSIX TZ
2270    strings, now use numeric time zone abbreviations instead of
2271    invented or obsolete alphanumeric abbreviations.  The affected
2272    zones are Antarctica/Casey, Antarctica/Davis,
2273    Antarctica/DumontDUrville, Antarctica/Mawson, Antarctica/Rothera,
2274    Antarctica/Syowa, Antarctica/Troll, Antarctica/Vostok,
2275    Asia/Anadyr, Asia/Ashgabat, Asia/Baku, Asia/Bishkek, Asia/Chita,
2276    Asia/Dushanbe, Asia/Irkutsk, Asia/Kamchatka, Asia/Khandyga,
2277    Asia/Krasnoyarsk, Asia/Magadan, Asia/Omsk, Asia/Sakhalin,
2278    Asia/Samarkand, Asia/Srednekolymsk, Asia/Tashkent, Asia/Tbilisi,
2279    Asia/Ust-Nera, Asia/Vladivostok, Asia/Yakutsk, Asia/Yekaterinburg,
2280    Asia/Yerevan, Etc/GMT-14, Etc/GMT-13, Etc/GMT-12, Etc/GMT-11,
2281    Etc/GMT-10, Etc/GMT-9, Etc/GMT-8, Etc/GMT-7, Etc/GMT-6, Etc/GMT-5,
2282    Etc/GMT-4, Etc/GMT-3, Etc/GMT-2, Etc/GMT-1, Etc/GMT+1, Etc/GMT+2,
2283    Etc/GMT+3, Etc/GMT+4, Etc/GMT+5, Etc/GMT+6, Etc/GMT+7, Etc/GMT+8,
2284    Etc/GMT+9, Etc/GMT+10, Etc/GMT+11, Etc/GMT+12, Europe/Kaliningrad,
2285    Europe/Minsk, Europe/Samara, Europe/Volgograd, and
2286    Indian/Kerguelen.  For Europe/Moscow the invented abbreviation MSM
2287    was replaced by +05, whereas MSK and MSD were kept as they are not
2288    our invention and are widely used.
2289
2290  Changes to zone names
2291
2292    Rename Asia/Rangoon to Asia/Yangon, with a backward compatibility link.
2293    (Thanks to David Massoud.)
2294
2295  Changes to code
2296
2297    zic no longer generates binary files containing POSIX TZ-like
2298    strings that disagree with the local time type after the last
2299    explicit transition in the data.  This fixes a bug with
2300    Africa/Casablanca and Africa/El_Aaiun in some year-2037 timestamps
2301    on the reference platform.  (Thanks to Alexander Belopolsky for
2302    reporting the bug and suggesting a way forward.)
2303
2304    If the installed localtime and/or posixrules files are symbolic
2305    links, zic now keeps them symbolic links when updating them, for
2306    compatibility with platforms like OpenSUSE where other programs
2307    configure these files as symlinks.
2308
2309    zic now avoids hard linking to symbolic links, avoids some
2310    unnecessary mkdir and stat system calls, and uses shorter file
2311    names internally.
2312
2313    zdump has a new -i option to generate transitions in a
2314    more-compact but still human-readable format.  This option is
2315    experimental, and the output format may change in future versions.
2316    (Thanks to Jon Skeet for suggesting that an option was needed,
2317    and thanks to Tim Parenti and Chris Rovick for further comments.)
2318
2319  Changes to build procedure
2320
2321    An experimental distribution format is available, in addition
2322    to the traditional format which will continue to be distributed.
2323    The new format is a tarball tzdb-VERSION.tar.lz with signature
2324    file tzdb-VERSION.tar.lz.asc.  It unpacks to a top-level directory
2325    tzdb-VERSION containing the code and data of the traditional
2326    two-tarball format, along with extra data that may be useful.
2327    (Thanks to Antonio Diaz Diaz, Oscar van Vlijmen, and many others
2328    for comments about the experimental format.)
2329
2330    The release version number is now more accurate in the usual case
2331    where releases are built from a Git repository.  For example, if
2332    23 commits and some working-file changes have been made since
2333    release 2016g, the version number is now something like
2334    '2016g-23-g50556e3-dirty' instead of the misleading '2016g'.
2335    Tagged releases use the same version number format as before,
2336    e.g., '2016g'.  To support the more-accurate version number, its
2337    specification has moved from a line in the Makefile to a new
2338    source file 'version'.
2339
2340    The experimental distribution contains a file to2050.tzs that
2341    contains what should be the output of 'zdump -i -c 2050' on
2342    primary zones.  If this file is available, 'make check' now checks
2343    that zdump generates this output.
2344
2345    'make check_web' now works on Fedora-like distributions.
2346
2347  Changes to documentation and commentary
2348
2349    tzfile.5 now documents the new restriction on POSIX TZ-like
2350    strings that is now implemented by zic.
2351
2352    Comments now cite URLs for some 1917-1921 Russian DST decrees.
2353    (Thanks to Alexander Belopolsky.)
2354
2355    tz-link.htm mentions JuliaTime (thanks to Curtis Vogt) and Time4J
2356    (thanks to Meno Hochschild) and ThreeTen-Extra, and its
2357    description of Java 8 has been brought up to date (thanks to
2358    Stephen Colebourne).  Its description of local time on Mars has
2359    been updated to match current practice, and URLs have been updated
2360    and some obsolete ones removed.
2361
2362
2363Release 2016f - 2016-07-05 16:26:51 +0200
2364
2365  Changes affecting future timestamps
2366
2367    The Egyptian government changed its mind on short notice, and
2368    Africa/Cairo will not introduce DST starting 2016-07-07 after all.
2369    (Thanks to Mina Samuel.)
2370
2371    Asia/Novosibirsk switches from +06 to +07 on 2016-07-24 at 02:00.
2372    (Thanks to Stepan Golosunov.)
2373
2374  Changes to past and future timestamps
2375
2376    Asia/Novokuznetsk and Asia/Novosibirsk now use numeric time zone
2377    abbreviations instead of invented ones.
2378
2379  Changes affecting past timestamps
2380
2381    Europe/Minsk's 1992-03-29 spring-forward transition was at 02:00 not 00:00.
2382    (Thanks to Stepan Golosunov.)
2383
2384
2385Release 2016e - 2016-06-14 08:46:16 -0700
2386
2387  Changes affecting future timestamps
2388
2389    Africa/Cairo observes DST in 2016 from July 7 to the end of October.
2390    Guess October 27 and 24:00 transitions.  (Thanks to Steffen Thorsen.)
2391    For future years, guess April's last Thursday to October's last
2392    Thursday except for Ramadan.
2393
2394  Changes affecting past timestamps
2395
2396    Locations while uninhabited now use '-00', not 'zzz', as a
2397    placeholder time zone abbreviation.  This is inspired by Internet
2398    RFC 3339 and is more consistent with numeric time zone
2399    abbreviations already used elsewhere.  The change affects several
2400    arctic and antarctic locations, e.g., America/Cambridge_Bay before
2401    1920 and Antarctica/Troll before 2005.
2402
2403    Asia/Baku's 1992-09-27 transition from +04 (DST) to +04 (non-DST) was
2404    at 03:00, not 23:00 the previous day.  (Thanks to Michael Deckers.)
2405
2406  Changes to code
2407
2408    zic now outputs a dummy transition at time 2**31 - 1 in zones
2409    whose POSIX-style TZ strings contain a '<'.  This mostly works
2410    around Qt bug 53071 <https://bugreports.qt.io/browse/QTBUG-53071>.
2411    (Thanks to Zhanibek Adilbekov for reporting the Qt bug.)
2412
2413  Changes affecting documentation and commentary
2414
2415    tz-link.htm says why governments should give plenty of notice for
2416    time zone or DST changes, and refers to Matt Johnson's blog post.
2417
2418    tz-link.htm mentions Tzdata for Elixir.  (Thanks to Matt Johnson.)
2419
2420
2421Release 2016d - 2016-04-17 22:50:29 -0700
2422
2423  Changes affecting future timestamps
2424
2425    America/Caracas switches from -0430 to -04 on 2016-05-01 at 02:30.
2426    (Thanks to Alexander Krivenyshev for the heads-up.)
2427
2428    Asia/Magadan switches from +10 to +11 on 2016-04-24 at 02:00.
2429    (Thanks to Alexander Krivenyshev and Matt Johnson.)
2430
2431    New zone Asia/Tomsk, split off from Asia/Novosibirsk.  It covers
2432    Tomsk Oblast, Russia, which switches from +06 to +07 on 2016-05-29
2433    at 02:00.  (Thanks to Stepan Golosunov.)
2434
2435  Changes affecting past timestamps
2436
2437    New zone Europe/Kirov, split off from Europe/Volgograd.  It covers
2438    Kirov Oblast, Russia, which switched from +04/+05 to +03/+04 on
2439    1989-03-26 at 02:00, roughly a year after Europe/Volgograd made
2440    the same change.  (Thanks to Stepan Golosunov.)
2441
2442    Russia and nearby locations had daylight-saving transitions on
2443    1992-03-29 at 02:00 and 1992-09-27 at 03:00, instead of on
2444    1992-03-28 at 23:00 and 1992-09-26 at 23:00.  (Thanks to Stepan
2445    Golosunov.)
2446
2447    Many corrections to historical time in Kazakhstan from 1991
2448    through 2005.  (Thanks to Stepan Golosunov.)  Replace Kazakhstan's
2449    invented time zone abbreviations with numeric abbreviations.
2450
2451  Changes to commentary
2452
2453    Mention Internet RFCs 7808 (TZDIST) and 7809 (CalDAV time zone references).
2454
2455
2456Release 2016c - 2016-03-23 00:51:27 -0700
2457
2458  Changes affecting future timestamps
2459
2460    Azerbaijan no longer observes DST.  (Thanks to Steffen Thorsen.)
2461
2462    Chile reverts from permanent to seasonal DST.  (Thanks to Juan
2463    Correa for the heads-up, and to Tim Parenti for corrections.)
2464    Guess that future transitions are August's and May's second
2465    Saturdays at 24:00 mainland time.  Also, call the period from
2466    2014-09-07 through 2016-05-14 daylight saving time instead of
2467    standard time, as that seems more appropriate now.
2468
2469  Changes affecting past timestamps
2470
2471    Europe/Kaliningrad and Europe/Vilnius changed from +03/+04 to
2472    +02/+03 on 1989-03-26, not 1991-03-31.  Europe/Volgograd changed
2473    from +04/+05 to +03/+04 on 1988-03-27, not 1989-03-26.
2474    (Thanks to Stepan Golosunov.)
2475
2476  Changes to commentary
2477
2478    Several updates and URLs for historical and proposed Russian changes.
2479    (Thanks to Stepan Golosunov, Matt Johnson, and Alexander Krivenyshev.)
2480
2481
2482Release 2016b - 2016-03-12 17:30:14 -0800
2483
2484  Compatibility note
2485
2486    Starting with release 2016b, some data entries cause zic implementations
2487    derived from tz releases 2005j through 2015e to issue warnings like
2488    "time zone abbreviation differs from POSIX standard (+03)".
2489    These warnings should not otherwise affect zic's output and can safely be
2490    ignored on today's platforms, as the warnings refer to a restriction in
2491    POSIX.1-1988 that was removed in POSIX.1-2001.  One way to suppress the
2492    warnings is to upgrade to zic derived from tz releases 2015f and later.
2493
2494  Changes affecting future timestamps
2495
2496    New zones Europe/Astrakhan and Europe/Ulyanovsk for Astrakhan and
2497    Ulyanovsk Oblasts, Russia, both of which will switch from +03 to +04 on
2498    2016-03-27 at 02:00 local time.  They need distinct zones since their
2499    post-1970 histories disagree.  New zone Asia/Barnaul for Altai Krai and
2500    Altai Republic, Russia, which will switch from +06 to +07 on the same date
2501    and local time.  The Astrakhan change is already official; the others have
2502    passed the first reading in the State Duma and are extremely likely.
2503    Also, Asia/Sakhalin moves from +10 to +11 on 2016-03-27 at 02:00.
2504    (Thanks to Alexander Krivenyshev for the heads-up, and to Matt Johnson
2505    and Stepan Golosunov for followup.)
2506
2507    As a trial of a new system that needs less information to be made up,
2508    the new zones use numeric time zone abbreviations like "+04"
2509    instead of invented abbreviations like "ASTT".
2510
2511    Haiti will not observe DST in 2016.  (Thanks to Jean Antoine via
2512    Steffen Thorsen.)
2513
2514    Palestine's spring-forward transition on 2016-03-26 is at 01:00, not 00:00.
2515    (Thanks to Hannah Kreitem.) Guess future transitions will be March's last
2516    Saturday at 01:00, not March's last Friday at 24:00.
2517
2518  Changes affecting past timestamps
2519
2520    Europe/Chisinau observed DST during 1990, and switched from +04 to
2521    +03 at 1990-05-06 02:00, instead of switching from +03 to +02.
2522    (Thanks to Stepan Golosunov.)
2523
2524    1991 abbreviations in Europe/Samara should be SAMT/SAMST, not
2525    KUYT/KUYST.  (Thanks to Stepan Golosunov.)
2526
2527  Changes to code
2528
2529    tzselect's diagnostics and checking, and checktab.awk's checking,
2530    have been improved.  (Thanks to J William Piggott.)
2531
2532    tzcode now builds under MinGW.  (Thanks to Ian Abbott and Esben Haabendal.)
2533
2534    tzselect now tests Julian-date TZ settings more accurately.
2535    (Thanks to J William Piggott.)
2536
2537  Changes to commentary
2538
2539    Comments in zone tables have been improved.  (Thanks to J William Piggott.)
2540
2541    tzselect again limits its menu comments so that menus fit on a
2542    24×80 alphanumeric display.
2543
2544    A new web page tz-how-to.html.  (Thanks to Bill Seymour.)
2545
2546    In the Theory file, the description of possible time zone abbreviations in
2547    tzdata has been cleaned up, as the old description was unclear and
2548    inconsistent.  (Thanks to Alain Mouette for reporting the problem.)
2549
2550
2551Release 2016a - 2016-01-26 23:28:02 -0800
2552
2553  Changes affecting future timestamps
2554
2555    America/Cayman will not observe daylight saving this year after all.
2556    Revert our guess that it would.  (Thanks to Matt Johnson.)
2557
2558    Asia/Chita switches from +0800 to +0900 on 2016-03-27 at 02:00.
2559    (Thanks to Alexander Krivenyshev.)
2560
2561    Asia/Tehran now has DST predictions for the year 2038 and later,
2562    to be March 21 00:00 to September 21 00:00.  This is likely better
2563    than predicting no DST, albeit off by a day every now and then.
2564
2565  Changes affecting past and future timestamps
2566
2567    America/Metlakatla switched from PST all year to AKST/AKDT on
2568    2015-11-01 at 02:00.  (Thanks to Steffen Thorsen.)
2569
2570    America/Santa_Isabel has been removed, and replaced with a
2571    backward compatibility link to America/Tijuana.  Its contents were
2572    apparently based on a misreading of Mexican legislation.
2573
2574  Changes affecting past timestamps
2575
2576    Asia/Karachi's two transition times in 2002 were off by a minute.
2577    (Thanks to Matt Johnson.)
2578
2579  Changes affecting build procedure
2580
2581    An installer can now combine leap seconds with use of the backzone file,
2582    e.g., with 'make PACKRATDATA=backzone REDO=posix_right zones'.
2583    The old 'make posix_packrat' rule is now marked as obsolescent.
2584    (Thanks to Ian Abbott for an initial implementation.)
2585
2586  Changes affecting documentation and commentary
2587
2588    A new file LICENSE makes it easier to see that the code and data
2589    are mostly public-domain.  (Thanks to James Knight.)  The three
2590    non-public-domain files now use the current (3-clause) BSD license
2591    instead of older versions of that license.
2592
2593    tz-link.htm mentions the BDE library (thanks to Andrew Paprocki),
2594    CCTZ (thanks to Tim Parenti), TimeJones.com, and has a new section
2595    on editing tz source files (with a mention of Sublime zoneinfo,
2596    thanks to Gilmore Davidson).
2597
2598    The Theory and asia files now mention the 2015 book "The Global
2599    Transformation of Time, 1870-1950", and cite a couple of reviews.
2600
2601    The America/Chicago entry now documents the informal use of US
2602    central time in Fort Pierre, South Dakota.  (Thanks to Rick
2603    McDermid, Matt Johnson, and Steve Jones.)
2604
2605
2606Release 2015g - 2015-10-01 00:39:51 -0700
2607
2608  Changes affecting future timestamps
2609
2610    Turkey's 2015 fall-back transition is scheduled for Nov. 8, not Oct. 25.
2611    (Thanks to Fatih.)
2612
2613    Norfolk moves from +1130 to +1100 on 2015-10-04 at 02:00 local time.
2614    (Thanks to Alexander Krivenyshev.)
2615
2616    Fiji's 2016 fall-back transition is scheduled for January 17, not 24.
2617    (Thanks to Ken Rylander.)
2618
2619    Fort Nelson, British Columbia will not fall back on 2015-11-01.  It has
2620    effectively been on MST (-0700) since it advanced its clocks on 2015-03-08.
2621    New zone America/Fort_Nelson.  (Thanks to Matt Johnson.)
2622
2623  Changes affecting past timestamps
2624
2625    Norfolk observed DST from 1974-10-27 02:00 to 1975-03-02 02:00.
2626
2627  Changes affecting code
2628
2629    localtime no longer mishandles America/Anchorage after 2037.
2630    (Thanks to Bradley White for reporting the bug.)
2631
2632    On hosts with signed 32-bit time_t, localtime no longer mishandles
2633    Pacific/Fiji after 2038-01-16 14:00 UTC.
2634
2635    The localtime module allows the variables 'timezone', 'daylight',
2636    and 'altzone' to be in common storage shared with other modules,
2637    and declares them in case the system <time.h> does not.
2638    (Problems reported by Kees Dekker.)
2639
2640    On platforms with tm_zone, strftime.c now assumes it is not NULL.
2641    This simplifies the code and is consistent with zdump.c.
2642    (Problem reported by Christos Zoulas.)
2643
2644  Changes affecting documentation
2645
2646   The tzfile man page now documents that transition times denote the
2647   starts (not the ends) of the corresponding time periods.
2648   (Ambiguity reported by Bill Seymour.)
2649
2650
2651Release 2015f - 2015-08-10 18:06:56 -0700
2652
2653  Changes affecting future timestamps
2654
2655    North Korea switches to +0830 on 2015-08-15.  (Thanks to Steffen Thorsen.)
2656    The abbreviation remains "KST".  (Thanks to Robert Elz.)
2657
2658    Uruguay no longer observes DST.  (Thanks to Steffen Thorsen
2659    and Pablo Camargo.)
2660
2661  Changes affecting past and future timestamps
2662
2663    Moldova starts and ends DST at 00:00 UTC, not at 01:00 UTC.
2664    (Thanks to Roman Tudos.)
2665
2666  Changes affecting data format and code
2667
2668    zic's '-y YEARISTYPE' option is no longer documented.  The TYPE
2669    field of a Rule line should now be '-'; the old values 'even',
2670    'odd', 'uspres', 'nonpres', 'nonuspres' were already undocumented.
2671    Although the implementation has not changed, these features do not
2672    work in the default installation, they are not used in the data,
2673    and they are now considered obsolescent.
2674
2675    zic now checks that two rules don't take effect at the same time.
2676    (Thanks to Jon Skeet and Arthur David Olson.)  Constraints on
2677    simultaneity are now documented.
2678
2679    The two characters '%z' in a zone format now stand for the UT
2680    offset, e.g., '-07' for seven hours behind UT and '+0530' for
2681    five hours and thirty minutes ahead.  This better supports time
2682    zone abbreviations conforming to POSIX.1-2001 and later.
2683
2684  Changes affecting installed data files
2685
2686    Comments for America/Halifax and America/Glace_Bay have been improved.
2687    (Thanks to Brian Inglis.)
2688
2689    Data entries have been simplified for Atlantic/Canary, Europe/Simferopol,
2690    Europe/Sofia, and Europe/Tallinn.  This yields slightly smaller
2691    installed data files for Europe/Simferopol and Europe/Tallinn.
2692    It does not affect timestamps.  (Thanks to Howard Hinnant.)
2693
2694  Changes affecting code
2695
2696    zdump and zic no longer warn about valid time zone abbreviations
2697    like '-05'.
2698
2699    Some Visual Studio 2013 warnings have been suppressed.
2700    (Thanks to Kees Dekker.)
2701
2702    'date' no longer sets the time of day and its -a, -d, -n and -t
2703    options have been removed.  Long obsolescent, the implementation
2704    of these features had porting problems.  Builders no longer need
2705    to configure HAVE_ADJTIME, HAVE_SETTIMEOFDAY, or HAVE_UTMPX_H.
2706    (Thanks to Kees Dekker for pointing out the problem.)
2707
2708  Changes affecting documentation
2709
2710    The Theory file mentions naming issues earlier, as these seem to be
2711    poorly publicized (thanks to Gilmore Davidson for reporting the problem).
2712
2713    tz-link.htm mentions Time Zone Database Parser (thanks to Howard Hinnant).
2714
2715    Mention that Herbert Samuel introduced the term "Summer Time".
2716
2717
2718Release 2015e - 2015-06-13 10:56:02 -0700
2719
2720  Changes affecting future timestamps
2721
2722    Morocco will suspend DST from 2015-06-14 03:00 through 2015-07-19 02:00,
2723    not 06-13 and 07-18 as we had guessed.  (Thanks to Milamber.)
2724
2725    Assume Cayman Islands will observe DST starting next year, using US rules.
2726    Although it isn't guaranteed, it is the most likely.
2727
2728  Changes affecting data format
2729
2730    The file 'iso3166.tab' now uses UTF-8, so that its entries can better
2731    spell the names of Åland Islands, Côte d'Ivoire, and Réunion.
2732
2733  Changes affecting code
2734
2735    When displaying data, tzselect converts it to the current locale's
2736    encoding if the iconv command works.  (Problem reported by random832.)
2737
2738    tzselect no longer mishandles Dominica, fixing a bug introduced
2739    in Release 2014f.  (Problem reported by Owen Leibman.)
2740
2741    zic -l no longer fails when compiled with -DTZDEFAULT=\"/etc/localtime\".
2742    This fixes a bug introduced in Release 2014f.
2743    (Problem reported by Leonardo Chiquitto.)
2744
2745
2746Release 2015d - 2015-04-24 08:09:46 -0700
2747
2748  Changes affecting future timestamps
2749
2750    Egypt will not observe DST in 2015 and will consider canceling it
2751    permanently.  For now, assume no DST indefinitely.
2752    (Thanks to Ahmed Nazmy and Tim Parenti.)
2753
2754  Changes affecting past timestamps
2755
2756    America/Whitehorse switched from UT -09 to -08 on 1967-05-28, not
2757    1966-07-01.  Also, Yukon's time zone history is documented better.
2758    (Thanks to Brian Inglis and Dennis Ferguson.)
2759
2760  Change affecting past and future time zone abbreviations
2761
2762    The abbreviations for Hawaii-Aleutian standard and daylight times
2763    have been changed from HAST/HADT to HST/HDT, as per US Government
2764    Printing Office style.  This affects only America/Adak since 1983,
2765    as America/Honolulu was already using the new style.
2766
2767  Changes affecting code
2768
2769   zic has some minor performance improvements.
2770
2771
2772Release 2015c - 2015-04-11 08:55:55 -0700
2773
2774  Changes affecting future timestamps
2775
2776    Egypt's spring-forward transition is at 24:00 on April's last Thursday,
2777    not 00:00 on April's last Friday.  2015's transition will therefore be on
2778    Thursday, April 30 at 24:00, not Friday, April 24 at 00:00.  Similar fixes
2779    apply to 2026, 2037, 2043, etc.  (Thanks to Steffen Thorsen.)
2780
2781  Changes affecting past timestamps
2782
2783    The following changes affect some pre-1991 Chile-related timestamps
2784    in America/Santiago, Antarctica/Palmer, and Pacific/Easter.
2785
2786      The 1910 transition was January 10, not January 1.
2787
2788      The 1918 transition was September 10, not September 1.
2789
2790      The UT -04 time observed from 1932 to 1942 is now considered to
2791      be standard time, not year-round DST.
2792
2793      Santiago observed DST (UT -03) from 1946-07-15 through
2794      1946-08-31, then reverted to standard time, then switched to -05
2795      on 1947-04-01.
2796
2797      Assume transitions before 1968 were at 00:00, since we have no data
2798      saying otherwise.
2799
2800      The spring 1988 transition was 1988-10-09, not 1988-10-02.
2801      The fall 1990 transition was 1990-03-11, not 1990-03-18.
2802
2803      Assume no UT offset change for Pacific/Easter on 1890-01-01,
2804      and omit all transitions on Pacific/Easter from 1942 through 1946
2805      since we have no data suggesting that they existed.
2806
2807    One more zone has been turned into a link, as it differed
2808    from an existing zone only for older timestamps.  As usual,
2809    this change affects UT offsets in pre-1970 timestamps only.
2810    The zone's old contents have been moved to the 'backzone' file.
2811    The affected zone is America/Montreal.
2812
2813  Changes affecting commentary
2814
2815    Mention the TZUpdater tool.
2816
2817    Mention "The Time Now".  (Thanks to Brandon Ramsey.)
2818
2819
2820Release 2015b - 2015-03-19 23:28:11 -0700
2821
2822  Changes affecting future timestamps
2823
2824    Mongolia will start observing DST again this year, from the last
2825    Saturday in March at 02:00 to the last Saturday in September at 00:00.
2826    (Thanks to Ganbold Tsagaankhuu.)
2827
2828    Palestine will start DST on March 28, not March 27.  Also,
2829    correct the fall 2014 transition from September 26 to October 24.
2830    Adjust future predictions accordingly.  (Thanks to Steffen Thorsen.)
2831
2832  Changes affecting past timestamps
2833
2834    The 1982 zone shift in Pacific/Easter has been corrected, fixing a 2015a
2835    regression.  (Thanks to Stuart Bishop for reporting the problem.)
2836
2837    Some more zones have been turned into links, when they differed
2838    from existing zones only for older timestamps.  As usual,
2839    these changes affect UT offsets in pre-1970 timestamps only.
2840    Their old contents have been moved to the 'backzone' file.
2841    The affected zones are: America/Antigua, America/Cayman,
2842    Pacific/Midway, and Pacific/Saipan.
2843
2844  Changes affecting time zone abbreviations
2845
2846    Correct the 1992-2010 DST abbreviation in Volgograd from "MSK" to "MSD".
2847    (Thanks to Hank W.)
2848
2849  Changes affecting code
2850
2851    Fix integer overflow bug in reference 'mktime' implementation.
2852    (Problem reported by Jörg Richter.)
2853
2854    Allow -Dtime_tz=time_t compilations, and allow -Dtime_tz=... libraries
2855    to be used in the same executable as standard-library time_t functions.
2856    (Problems reported by Bradley White.)
2857
2858  Changes affecting commentary
2859
2860    Cite the recent Mexican decree changing Quintana Roo's time zone.
2861    (Thanks to Carlos Raúl Perasso.)
2862
2863    Likewise for the recent Chilean decree.  (Thanks to Eduardo Romero Urra.)
2864
2865    Update info about Mars time.
2866
2867
2868Release 2015a - 2015-01-29 22:35:20 -0800
2869
2870  Changes affecting future timestamps
2871
2872    The Mexican state of Quintana Roo, represented by America/Cancun,
2873    will shift from Central Time with DST to Eastern Time without DST
2874    on 2015-02-01 at 02:00.  (Thanks to Steffen Thorsen and Gwillim Law.)
2875
2876    Chile will not change clocks in April or thereafter; its new standard time
2877    will be its old daylight saving time.  This affects America/Santiago,
2878    Pacific/Easter, and Antarctica/Palmer.  (Thanks to Juan Correa.)
2879
2880    New leap second 2015-06-30 23:59:60 UTC as per IERS Bulletin C 49.
2881    (Thanks to Tim Parenti.)
2882
2883  Changes affecting past timestamps
2884
2885    Iceland observed DST in 1919 and 1921, and its 1939 fallback
2886    transition was Oct. 29, not Nov. 29.  Remove incorrect data from
2887    Shanks about time in Iceland between 1837 and 1908.
2888
2889    Some more zones have been turned into links, when they differed
2890    from existing zones only for older timestamps.  As usual,
2891    these changes affect UT offsets in pre-1970 timestamps only.
2892    Their old contents have been moved to the 'backzone' file.
2893    The affected zones are: Asia/Aden, Asia/Bahrain, Asia/Kuwait,
2894    and Asia/Muscat.
2895
2896  Changes affecting code
2897
2898    tzalloc now scrubs time zone abbreviations compatibly with the way
2899    that tzset always has, by replacing invalid bytes with '_' and by
2900    shortening too-long abbreviations.
2901
2902    tzselect ports to POSIX awk implementations, no longer mishandles
2903    POSIX TZ settings when GNU awk is used, and reports POSIX TZ
2904    settings to the user.  (Thanks to Stefan Kuhn.)
2905
2906  Changes affecting build procedure
2907
2908    'make check' now checks for links to links in the data.
2909    One such link (for Africa/Asmera) has been fixed.
2910    (Thanks to Stephen Colebourne for pointing out the problem.)
2911
2912  Changes affecting commentary
2913
2914    The leapseconds file commentary now mentions the expiration date.
2915    (Problem reported by Martin Burnicki.)
2916
2917    Update Mexican Library of Congress URL.
2918
2919
2920Release 2014j - 2014-11-10 17:37:11 -0800
2921
2922  Changes affecting current and future timestamps
2923
2924    Turks & Caicos' switch from US eastern time to UT -04 year-round
2925    did not occur on 2014-11-02 at 02:00.  It's currently scheduled
2926    for 2015-11-01 at 02:00.  (Thanks to Chris Walton.)
2927
2928  Changes affecting past timestamps
2929
2930    Many pre-1989 timestamps have been corrected for Asia/Seoul and
2931    Asia/Pyongyang, based on sources for the Korean-language Wikipedia
2932    entry for time in Korea.  (Thanks to Sanghyuk Jung.)  Also, no
2933    longer guess that Pyongyang mimicked Seoul time after World War II,
2934    as this is politically implausible.
2935
2936    Some more zones have been turned into links, when they differed
2937    from existing zones only for older timestamps.  As usual,
2938    these changes affect UT offsets in pre-1970 timestamps only.
2939    Their old contents have been moved to the 'backzone' file.
2940    The affected zones are: Africa/Addis_Ababa, Africa/Asmara,
2941    Africa/Dar_es_Salaam, Africa/Djibouti, Africa/Kampala,
2942    Africa/Mogadishu, Indian/Antananarivo, Indian/Comoro, and
2943    Indian/Mayotte.
2944
2945  Changes affecting commentary
2946
2947    The commentary is less enthusiastic about Shanks as a source,
2948    and is more careful to distinguish UT from UTC.
2949
2950
2951Release 2014i - 2014-10-21 22:04:57 -0700
2952
2953  Changes affecting future timestamps
2954
2955    Pacific/Fiji will observe DST from 2014-11-02 02:00 to 2015-01-18 03:00.
2956    (Thanks to Ken Rylander for the heads-up.)  Guess that future
2957    years will use a similar pattern.
2958
2959    A new Zone Pacific/Bougainville, for the part of Papua New Guinea
2960    that plans to switch from UT +10 to +11 on 2014-12-28 at 02:00.
2961    (Thanks to Kiley Walbom for the heads-up.)
2962
2963  Changes affecting time zone abbreviations
2964
2965    Since Belarus is not changing its clocks even though Moscow is,
2966    the time zone abbreviation in Europe/Minsk is changing from FET
2967    to its more-traditional value MSK on 2014-10-26 at 01:00.
2968    (Thanks to Alexander Bokovoy for the heads-up about Belarus.)
2969
2970    The new abbreviation IDT stands for the pre-1976 use of UT +08 in
2971    Indochina, to distinguish it better from ICT (+07).
2972
2973  Changes affecting past timestamps
2974
2975    Many timestamps have been corrected for Asia/Ho_Chi_Minh before 1976
2976    (thanks to Trần Ngọc Quân for an indirect pointer to Trần Tiến Bình's
2977    authoritative book).  Asia/Ho_Chi_Minh has been added to
2978    zone1970.tab, to give tzselect users in Vietnam two choices,
2979    since north and south Vietnam disagreed after our 1970 cutoff.
2980
2981    Asia/Phnom_Penh and Asia/Vientiane have been turned into links, as
2982    they differed from existing zones only for older timestamps.  As
2983    usual, these changes affect pre-1970 timestamps only.  Their old
2984    contents have been moved to the 'backzone' file.
2985
2986  Changes affecting code
2987
2988    The time-related library functions now set errno on failure, and
2989    some crashes in the new tzalloc-related library functions have
2990    been fixed.  (Thanks to Christos Zoulas for reporting most of
2991    these problems and for suggesting fixes.)
2992
2993    If USG_COMPAT is defined and the requested timestamp is standard time,
2994    the tz library's localtime and mktime functions now set the extern
2995    variable timezone to a value appropriate for that timestamp; and
2996    similarly for ALTZONE, daylight saving time, and the altzone variable.
2997    This change is a companion to the tzname change in 2014h, and is
2998    designed to make timezone and altzone more compatible with tzname.
2999
3000    The tz library's functions now set errno to EOVERFLOW if they fail
3001    because the result cannot be represented.  ctime and ctime_r now
3002    return NULL and set errno when a timestamp is out of range, rather
3003    than having undefined behavior.
3004
3005    Some bugs associated with the new 2014g functions have been fixed.
3006    This includes a bug that largely incapacitated the new functions
3007    time2posix_z and posix2time_z.  (Thanks to Christos Zoulas.)
3008    It also includes some uses of uninitialized variables after tzalloc.
3009    The new code uses the standard type 'ssize_t', which the Makefile
3010    now gives porting advice about.
3011
3012  Changes affecting commentary
3013
3014    Updated URLs for NRC Canada (thanks to Matt Johnson and Brian Inglis).
3015
3016
3017Release 2014h - 2014-09-25 18:59:03 -0700
3018
3019  Changes affecting past timestamps
3020
3021    America/Jamaica's 1974 spring-forward transition was Jan. 6, not Apr. 28.
3022
3023    Shanks says Asia/Novokuznetsk switched from LMT (not "NMT") on 1924-05-01,
3024    not 1920-01-06.  The old entry was based on a misinterpretation of Shanks.
3025
3026    Some more zones have been turned into links, when they differed
3027    from existing zones only for older timestamps.  As usual,
3028    these changes affect UT offsets in pre-1970 timestamps only.
3029    Their old contents have been moved to the 'backzone' file.
3030    The affected zones are: Africa/Blantyre, Africa/Bujumbura,
3031    Africa/Gaborone, Africa/Harare, Africa/Kigali, Africa/Lubumbashi,
3032    Africa/Lusaka, Africa/Maseru, and Africa/Mbabane.
3033
3034  Changes affecting code
3035
3036    zdump -V and -v now output gmtoff= values on all platforms,
3037    not merely on platforms defining TM_GMTOFF.
3038
3039    The tz library's localtime and mktime functions now set tzname to a value
3040    appropriate for the requested timestamp, and zdump now uses this
3041    on platforms not defining TM_ZONE, fixing a 2014g regression.
3042    (Thanks to Tim Parenti for reporting the problem.)
3043
3044    The tz library no longer sets tzname if localtime or mktime fails.
3045
3046    zdump -c no longer mishandles transitions near year boundaries.
3047    (Thanks to Tim Parenti for reporting the problem.)
3048
3049    An access to uninitialized data has been fixed.
3050    (Thanks to Jörg Richter for reporting the problem.)
3051
3052    When THREAD_SAFE is defined, the code ports to the C11 memory model.
3053    A memory leak has been fixed if ALL_STATE and THREAD_SAFE are defined
3054    and two threads race to initialize data used by gmtime-like functions.
3055    (Thanks to Andy Heninger for reporting the problems.)
3056
3057  Changes affecting build procedure
3058
3059    'make check' now checks better for properly-sorted data.
3060
3061  Changes affecting documentation and commentary
3062
3063    zdump's gmtoff=N output is now documented, and its isdst=D output
3064    is now documented to possibly output D values other than 0 or 1.
3065
3066    zdump -c's treatment of years is now documented to use the
3067    Gregorian calendar and Universal Time without leap seconds,
3068    and its behavior at cutoff boundaries is now documented better.
3069    (Thanks to Arthur David Olson and Tim Parenti for reporting the problems.)
3070
3071    Programs are now documented to use the proleptic Gregorian calendar.
3072    (Thanks to Alan Barrett for the suggestion.)
3073
3074    Fractional-second GMT offsets have been documented for civil time
3075    in 19th-century Chennai, Jakarta, and New York.
3076
3077
3078Release 2014g - 2014-08-28 12:31:23 -0700
3079
3080  Changes affecting future timestamps
3081
3082    Turks & Caicos is switching from US eastern time to UT -04
3083    year-round, modeled as a switch on 2014-11-02 at 02:00.
3084    [As noted in 2014j, this switch was later delayed.]
3085
3086  Changes affecting past timestamps
3087
3088    Time in Russia or the USSR before 1926 or so has been corrected by
3089    a few seconds in the following zones: Asia/Irkutsk,
3090    Asia/Krasnoyarsk, Asia/Omsk, Asia/Samarkand, Asia/Tbilisi,
3091    Asia/Vladivostok, Asia/Yakutsk, Europe/Riga, Europe/Samara.  For
3092    Asia/Yekaterinburg the correction is a few minutes.  (Thanks to
3093    Vladimir Karpinsky.)
3094
3095    The Portuguese decree of 1911-05-26 took effect on 1912-01-01.
3096    This affects 1911 timestamps in Africa/Bissau, Africa/Luanda,
3097    Atlantic/Azores, and Atlantic/Madeira.  Also, Lisbon's pre-1912
3098    GMT offset was -0:36:45 (rounded from -0:36:44.68), not -0:36:32.
3099    (Thanks to Stephen Colebourne for pointing to the decree.)
3100
3101    Asia/Dhaka ended DST on 2009-12-31 at 24:00, not 23:59.
3102
3103    A new file 'backzone' contains data which may appeal to
3104    connoisseurs of old timestamps, although it is out of scope for
3105    the tz database, is often poorly sourced, and contains some data
3106    that is known to be incorrect.  The new file is not recommended
3107    for ordinary use and its entries are not installed by default.
3108    (Thanks to Lester Caine for the high-quality Jersey, Guernsey, and
3109    Isle of Man entries.)
3110
3111    Some more zones have been turned into links, when they differed
3112    from existing zones only for older timestamps.  As usual,
3113    these changes affect UT offsets in pre-1970 timestamps only.
3114    Their old contents have been moved to the 'backzone' file.
3115    The affected zones are: Africa/Bangui, Africa/Brazzaville,
3116    Africa/Douala, Africa/Kinshasa, Africa/Libreville, Africa/Luanda,
3117    Africa/Malabo, Africa/Niamey, and Africa/Porto-Novo.
3118
3119  Changes affecting code
3120
3121    Unless NETBSD_INSPIRED is defined to 0, the tz library now
3122    supplies functions for creating and using objects that represent
3123    timezones. The new functions are tzalloc, tzfree, localtime_rz,
3124    mktime_z, and (if STD_INSPIRED is also defined) posix2time_z and
3125    time2posix_z.  They are intended for performance: for example,
3126    localtime_rz (unlike localtime_r) is trivially thread-safe without
3127    locking.  (Thanks to Christos Zoulas for proposing NetBSD-inspired
3128    functions, and to Alan Barrett and Jonathan Lennox for helping to
3129    debug the change.)
3130
3131    zdump now builds with the tz library unless USE_LTZ is defined to 0,
3132    This lets zdump use tz features even if the system library lacks them.
3133    To build zdump with the system library, use 'make CFLAGS=-DUSE_LTZ=0
3134    TZDOBJS=zdump.o CHECK_TIME_T_ALTERNATIVES='.
3135
3136    zdump now uses localtime_rz if available, as it's significantly faster,
3137    and it can help zdump better diagnose invalid timezone names.
3138    Define HAVE_LOCALTIME_RZ to 0 to suppress this.  HAVE_LOCALTIME_RZ
3139    defaults to 1 if NETBSD_INSPIRED && USE_LTZ.  When localtime_rz is
3140    not available, zdump now uses localtime_r and tzset if available,
3141    as this is a bit cleaner and faster than plain localtime.  Compile
3142    with -DHAVE_LOCALTIME_R=0 and/or -DHAVE_TZSET=0 if your system
3143    lacks these two functions.
3144
3145    If THREAD_SAFE is defined to 1, the tz library is now thread-safe.
3146    Although not needed for tz's own applications, which are single-threaded,
3147    this supports POSIX better if the tz library is used in multithreaded apps.
3148
3149    Some crashes have been fixed when zdump or the tz library is given
3150    invalid or outlandish input.
3151
3152    The tz library no longer mishandles leap seconds on platforms with
3153    unsigned time_t in timezones that lack ordinary transitions after 1970.
3154
3155    The tz code now attempts to infer TM_GMTOFF and TM_ZONE if not
3156    already defined, to make it easier to configure on common platforms.
3157    Define NO_TM_GMTOFF and NO_TM_ZONE to suppress this.
3158
3159    Unless the new macro UNINIT_TRAP is defined to 1, the tz code now
3160    assumes that reading uninitialized memory yields garbage values
3161    but does not cause other problems such as traps.
3162
3163    If TM_GMTOFF is defined and UNINIT_TRAP is 0, mktime is now
3164    more likely to guess right for ambiguous timestamps near
3165    transitions where tm_isdst does not change.
3166
3167    If HAVE_STRFTIME_L is defined to 1, the tz library now defines
3168    strftime_l for compatibility with recent versions of POSIX.
3169    Only the C locale is supported, though.  HAVE_STRFTIME_L defaults
3170    to 1 on recent POSIX versions, and to 0 otherwise.
3171
3172    tzselect -c now uses a hybrid distance measure that works better
3173    in Africa.  (Thanks to Alan Barrett for noting the problem.)
3174
3175    The C source code now ports to NetBSD when GCC_DEBUG_FLAGS is used,
3176    or when time_tz is defined.
3177
3178    When HAVE_UTMPX_H is set the 'date' command now builds on systems
3179    whose <utmpx.h> file does not define WTMPX_FILE, and when setting
3180    the date it updates the wtmpx file if _PATH_WTMPX is defined.
3181    This affects GNU/Linux and similar systems.
3182
3183    For easier maintenance later, some C code has been simplified,
3184    some lint has been removed, and the code has been tweaked so that
3185    plain 'make' is more likely to work.
3186
3187    The C type 'bool' is now used for boolean values, instead of 'int'.
3188
3189    The long-obsolete LOCALE_HOME code has been removed.
3190
3191    The long-obsolete 'gtime' function has been removed.
3192
3193  Changes affecting build procedure
3194
3195    'zdump' no longer links in ialloc.o, as it's not needed.
3196
3197    'make check_time_t_alternatives' no longer assumes GNU diff.
3198
3199  Changes affecting distribution tarballs
3200
3201    The files checktab.awk and zoneinfo2tdf.pl are now distributed in
3202    the tzdata tarball instead of the tzcode tarball, since they help
3203    maintain the data.  The NEWS and Theory files are now also
3204    distributed in the tzdata tarball, as they're relevant for data.
3205    (Thanks to Alan Barrett for pointing this out.)  Also, the
3206    leapseconds.awk file is no longer distributed in the tzcode
3207    tarball, since it belongs in the tzdata tarball (where 2014f
3208    inadvertently also distributed it).
3209
3210  Changes affecting documentation and commentary
3211
3212    A new file CONTRIBUTING is distributed.  (Thanks to Tim Parenti for
3213    suggesting a CONTRIBUTING file, and to Tony Finch and Walter Harms
3214    for debugging it.)
3215
3216    The man pages have been updated to use function prototypes,
3217    to document thread-safe variants like localtime_r, and to document
3218    the NetBSD-inspired functions tzalloc, tzfree, localtime_rz, and
3219    mktime_z.
3220
3221    The fields in Link lines have been renamed to be more descriptive
3222    and more like the parameters of 'ln'.  LINK-FROM has become TARGET,
3223    and LINK-TO has become LINK-NAME.
3224
3225    tz-link.htm mentions the IETF's tzdist working group; Windows
3226    Runtime etc. (thanks to Matt Johnson); and HP-UX's tztab.
3227
3228    Some broken URLs have been fixed in the commentary.  (Thanks to
3229    Lester Caine.)
3230
3231    Commentary about Philippines DST has been updated, and commentary
3232    on pre-1970 time in India has been added.
3233
3234
3235Release 2014f - 2014-08-05 17:42:36 -0700
3236
3237  Changes affecting future timestamps
3238
3239    Russia will subtract an hour from most of its time zones on 2014-10-26
3240    at 02:00 local time.  (Thanks to Alexander Krivenyshev.)
3241    There are a few exceptions: Magadan Oblast (Asia/Magadan) and Zabaykalsky
3242    Krai are subtracting two hours; conversely, Chukotka Autonomous Okrug
3243    (Asia/Anadyr), Kamchatka Krai (Asia/Kamchatka), Kemerovo Oblast
3244    (Asia/Novokuznetsk), and the Samara Oblast and the Udmurt Republic
3245    (Europe/Samara) are not changing their clocks.  The changed zones are
3246    Europe/Kaliningrad, Europe/Moscow, Europe/Simferopol, Europe/Volgograd,
3247    Asia/Yekaterinburg, Asia/Omsk, Asia/Novosibirsk, Asia/Krasnoyarsk,
3248    Asia/Irkutsk, Asia/Yakutsk, Asia/Vladivostok, Asia/Khandyga,
3249    Asia/Sakhalin, and Asia/Ust-Nera; Asia/Magadan will have two hours
3250    subtracted; and Asia/Novokuznetsk's time zone abbreviation is affected,
3251    but not its UTC offset.  Two zones are added: Asia/Chita (split
3252    from Asia/Yakutsk, and also with two hours subtracted) and
3253    Asia/Srednekolymsk (split from Asia/Magadan, but with only one hour
3254    subtracted).  (Thanks to Tim Parenti for much of the above.)
3255
3256  Changes affecting time zone abbreviations
3257
3258    Australian eastern time zone abbreviations are now AEST/AEDT not EST,
3259    and similarly for the other Australian zones.  That is, for eastern
3260    standard and daylight saving time the abbreviations are AEST and AEDT
3261    instead of the former EST for both; similarly, ACST/ACDT, ACWST/ACWDT,
3262    and AWST/AWDT are now used instead of the former CST, CWST, and WST.
3263    This change does not affect UT offsets, only time zone abbreviations.
3264    (Thanks to Rich Tibbett and many others.)
3265
3266    Asia/Novokuznetsk shifts from NOVT to KRAT (remaining on UT +07)
3267    effective 2014-10-26 at 02:00 local time.
3268
3269    The time zone abbreviation for Xinjiang Time (observed in Ürümqi)
3270    has been changed from URUT to XJT.  (Thanks to Luther Ma.)
3271
3272    Prefer MSK/MSD for Moscow time in Russia, even in other cities.
3273    Similarly, prefer EET/EEST for eastern European time in Russia.
3274
3275    Change time zone abbreviations in (western) Samoa to use "ST" and
3276    "DT" suffixes, as this is more likely to match common practice.
3277    Prefix "W" to (western) Samoa time when its standard-time offset
3278    disagrees with that of American Samoa.
3279
3280    America/Metlakatla now uses PST, not MeST, to abbreviate its time zone.
3281
3282    Time zone abbreviations have been updated for Japan's two time
3283    zones used 1896-1937.  JWST now stands for Western Standard
3284    Time, and JCST for Central Standard Time (formerly this was CJT).
3285    These abbreviations are now used for time in Korea, Taiwan,
3286    and Sakhalin while controlled by Japan.
3287
3288  Changes affecting past timestamps
3289
3290    China's five zones have been simplified to two, since the post-1970
3291    differences in the other three seem to have been imaginary.  The
3292    zones Asia/Harbin, Asia/Chongqing, and Asia/Kashgar have been
3293    removed; backwards-compatibility links still work, albeit with
3294    different behaviors for timestamps before May 1980.  Asia/Urumqi's
3295    1980 transition to UT +08 has been removed, so that it is now at
3296    +06 and not +08.  (Thanks to Luther Ma and to Alois Treindl;
3297    Treindl sent helpful translations of two papers by Guo Qingsheng.)
3298
3299    Some zones have been turned into links, when they differed from existing
3300    zones only for older UT offsets where data entries were likely invented.
3301    These changes affect UT offsets in pre-1970 timestamps only.  This is
3302    similar to the change in release 2013e, except this time for western
3303    Africa.  The affected zones are: Africa/Bamako, Africa/Banjul,
3304    Africa/Conakry, Africa/Dakar, Africa/Freetown, Africa/Lome,
3305    Africa/Nouakchott, Africa/Ouagadougou, Africa/Sao_Tome, and
3306    Atlantic/St_Helena.  This also affects the backwards-compatibility
3307    link Africa/Timbuktu.  (Thanks to Alan Barrett, Stephen Colebourne,
3308    Tim Parenti, and David Patte for reporting problems in earlier
3309    versions of this change.)
3310
3311    Asia/Shanghai's pre-standard-time UT offset has been changed from
3312    8:05:57 to 8:05:43, the location of Xujiahui Observatory.  Its
3313    transition to standard time has been changed from 1928 to 1901.
3314
3315    Asia/Taipei switched to JWST on 1896-01-01, then to JST on 1937-10-01,
3316    then to CST on 1945-09-21 at 01:00, and did not observe DST in 1945.
3317    In 1946 it observed DST from 05-15 through 09-30; in 1947
3318    from 04-15 through 10-31; and in 1979 from 07-01 through 09-30.
3319    (Thanks to Yu-Cheng Chuang.)
3320
3321    Asia/Riyadh's transition to standard time is now 1947-03-14, not 1950.
3322
3323    Europe/Helsinki's 1942 fall-back transition was 10-04 at 01:00, not
3324    10-03 at 00:00.  (Thanks to Konstantin Hyppönen.)
3325
3326    Pacific/Pago_Pago has been changed from UT -11:30 to -11 for the
3327    period from 1911 to 1950.
3328
3329    Pacific/Chatham has been changed to New Zealand standard time plus
3330    45 minutes for the period before 1957, reflecting a 1956 remark in
3331    the New Zealand parliament.
3332
3333    Europe/Budapest has several pre-1946 corrections: in 1918 the transition
3334    out of DST was on 09-16, not 09-29; in 1919 it was on 11-24, not 09-15; in
3335    1945 it was on 11-01, not 11-03; in 1941 the transition to DST was 04-08
3336    not 04-06 at 02:00; and there was no DST in 1920.
3337
3338    Africa/Accra is now assumed to have observed DST from 1920 through 1935.
3339
3340    Time in Russia before 1927 or so has been corrected by a few seconds in
3341    the following zones: Europe/Moscow, Asia/Irkutsk, Asia/Tbilisi,
3342    Asia/Tashkent, Asia/Vladivostok, Asia/Yekaterinburg, Europe/Helsinki, and
3343    Europe/Riga.  Also, Moscow's location has been changed to its Kilometer 0
3344    point.  (Thanks to Vladimir Karpinsky for the Moscow changes.)
3345
3346  Changes affecting data format
3347
3348    A new file 'zone1970.tab' supersedes 'zone.tab' in the installed data.
3349    The new file's extended format allows multiple country codes per zone.
3350    The older file is still installed but is deprecated; its format is
3351    not changing and it will still be distributed for a while, but new
3352    applications should use the new file.
3353
3354    The new file format simplifies maintenance of obscure locations.
3355    To test this, it adds coverage for the Crozet Islands and the
3356    Scattered Islands.  (Thanks to Tobias Conradi and Antoine Leca.)
3357
3358    The file 'iso3166.tab' is planned to switch from ASCII to UTF-8.
3359    It is still ASCII now, but commentary about the switch has been added.
3360    The new file 'zone1970.tab' already uses UTF-8.
3361
3362  Changes affecting code
3363
3364    'localtime', 'mktime', etc. now use much less stack space if ALL_STATE
3365    is defined.  (Thanks to Elliott Hughes for reporting the problem.)
3366
3367    'zic' no longer mishandles input when ignoring case in locales that
3368    are not compatible with English, e.g., unibyte Turkish locales when
3369    compiled with HAVE_GETTEXT.
3370
3371    Error diagnostics of 'zic' and 'yearistype' have been reworded so that
3372    they no longer use ASCII '-' as if it were a dash.
3373
3374    'zic' now rejects output file names that contain '.' or '..' components.
3375    (Thanks to Tim Parenti for reporting the problem.)
3376
3377    'zic -v' now warns about output file names that do not follow
3378    POSIX rules, or that contain a digit or '.'.  (Thanks to Arthur
3379    David Olson for starting the ball rolling on this.)
3380
3381    Some lint has been removed when using GCC_DEBUG_FLAGS with GCC 4.9.0.
3382
3383  Changes affecting build procedure
3384
3385    'zic' no longer links in localtime.o and asctime.o, as they're not needed.
3386    (Thanks to John Cochran.)
3387
3388  Changes affecting documentation and commentary
3389
3390    The 'Theory' file documents legacy names, the longstanding
3391    exceptions to the POSIX-inspired file name rules.
3392
3393    The 'zic' documentation clarifies the role of time types when
3394    interpreting dates.  (Thanks to Arthur David Olson.)
3395
3396    Documentation and commentary now prefer UTF-8 to US-ASCII,
3397    allowing the use of proper accents in foreign words and names.
3398    Code and data have not changed because of this.  (Thanks to
3399    Garrett Wollman, Ian Abbott, and Guy Harris for helping to debug
3400    this.)
3401
3402    Non-HTML documentation and commentary now use plain-text URLs instead of
3403    HTML insertions, and are more consistent about bracketing URLs when they
3404    are not already surrounded by white space.  (Thanks to suggestions by
3405    Steffen Nurpmeso.)
3406
3407    There is new commentary about Xujiahui Observatory, the five time-zone
3408    project in China from 1918 to 1949, timekeeping in Japanese-occupied
3409    Shanghai, and Tibet Time in the 1950s.  The sharp-eyed can spot the
3410    warlord Jin Shuren in the data.
3411
3412    Commentary about the coverage of each Russian zone has been standardized.
3413    (Thanks to Tim Parenti.)
3414
3415    There is new commentary about contemporary timekeeping in Ethiopia.
3416
3417    Obsolete comments about a 2007 proposal for DST in Kuwait has been removed.
3418
3419    There is new commentary about time in Poland in 1919.
3420
3421    Proper credit has been given to DST inventor George Vernon Hudson.
3422
3423    Commentary about time in Metlakatla, AK and Resolute, NU has been
3424    improved, with a new source for the former.
3425
3426    In zone.tab, Pacific/Easter no longer mentions Salas y Gómez, as it
3427    is uninhabited.
3428
3429    Commentary about permanent Antarctic bases has been updated.
3430
3431    Several typos have been corrected.  (Thanks to Tim Parenti for
3432    contributing some of these fixes.)
3433
3434    tz-link.htm now mentions the JavaScript libraries Moment Timezone,
3435    TimezoneJS.Date, Walltime-js, and Timezone.  (Thanks to a heads-up
3436    from Matt Johnson.)  Also, it mentions the Go 'latlong' package.
3437    (Thanks to a heads-up from Dirkjan Ochtman.)
3438
3439    The files usno1988, usno1989, usno1989a, usno1995, usno1997, and usno1998
3440    have been removed.  These obsolescent US Naval Observatory entries were no
3441    longer helpful for maintenance.  (Thanks to Tim Parenti for the suggestion.)
3442
3443
3444Release 2014e - 2014-06-12 21:53:52 -0700
3445
3446  Changes affecting near-future timestamps
3447
3448    Egypt's 2014 Ramadan-based transitions are June 26 and July 31 at 24:00.
3449    (Thanks to Imed Chihi.)  Guess that from 2015 on Egypt will temporarily
3450    switch to standard time at 24:00 the last Thursday before Ramadan, and
3451    back to DST at 00:00 the first Friday after Ramadan.
3452
3453    Similarly, Morocco's are June 28 at 03:00 and August 2 at 02:00.  (Thanks
3454    to Milamber Space Network.)  Guess that from 2015 on Morocco will
3455    temporarily switch to standard time at 03:00 the last Saturday before
3456    Ramadan, and back to DST at 02:00 the first Saturday after Ramadan.
3457
3458  Changes affecting past timestamps
3459
3460    The abbreviation "MSM" (Moscow Midsummer Time) is now used instead of
3461    "MSD" for Moscow's double daylight time in summer 1921.  Also, a typo
3462    "VLASST" has been repaired to be "VLAST" for Vladivostok summer time
3463    in 1991.  (Thanks to Hank W. for reporting the problems.)
3464
3465  Changes affecting commentary
3466
3467    tz-link.htm now cites RFC 7265 for jCal, mentions PTP and the
3468    draft CalDAV extension, updates URLs for TSP, TZInfo, IATA, and
3469    removes stale pointers to World Time Explorer and WORLDTIME.
3470
3471
3472Release 2014d - 2014-05-27 21:34:40 -0700
3473
3474  Changes affecting code
3475
3476    zic no longer generates files containing timestamps before the Big Bang.
3477    This works around GNOME glib bug 878
3478    <https://gitlab.gnome.org/GNOME/glib/issues/878>
3479    (Thanks to Leonardo Chiquitto for reporting the bug, and to
3480    Arthur David Olson and James Cloos for suggesting improvements to the fix.)
3481
3482  Changes affecting documentation
3483
3484    tz-link.htm now mentions GNOME.
3485
3486
3487Release 2014c - 2014-05-13 07:44:13 -0700
3488
3489  Changes affecting near-future timestamps
3490
3491    Egypt observes DST starting 2014-05-15 at 24:00.
3492    (Thanks to Ahmad El-Dardiry and Gunther Vermier.)
3493    Details have not been announced, except that DST will not be observed
3494    during Ramadan.  Guess that DST will stop during the same Ramadan dates as
3495    Morocco, and that Egypt's future spring and fall transitions will be the
3496    same as 2010 when it last observed DST, namely April's last Friday at
3497    00:00 to September's last Thursday at 23:00 standard time.  Also, guess
3498    that Ramadan transitions will be at 00:00 standard time.
3499
3500  Changes affecting code
3501
3502    zic now generates transitions for minimum time values, eliminating guesswork
3503    when handling low-valued timestamps.  (Thanks to Arthur David Olson.)
3504
3505    Port to Cygwin sans glibc.  (Thanks to Arthur David Olson.)
3506
3507  Changes affecting commentary and documentation
3508
3509    Remove now-confusing comment about Jordan.  (Thanks to Oleksii Nochovnyi.)
3510
3511
3512Release 2014b - 2014-03-24 21:28:50 -0700
3513
3514  Changes affecting near-future timestamps
3515
3516    Crimea switches to Moscow time on 2014-03-30 at 02:00 local time.
3517    (Thanks to Alexander Krivenyshev.)  Move its zone.tab entry from UA to RU.
3518
3519    New entry for Troll station, Antarctica.  (Thanks to Paul-Inge Flakstad and
3520    Bengt-Inge Larsson.)  This is currently an approximation; a better version
3521    will require the zic and localtime fixes mentioned below, and the plan is
3522    to wait for a while until at least the zic fixes propagate.
3523
3524  Changes affecting code
3525
3526    'zic' and 'localtime' no longer reject locations needing four transitions
3527    per year for the foreseeable future.  (Thanks to Andrew Main (Zefram).)
3528    Also, 'zic' avoids some unlikely failures due to integer overflow.
3529
3530  Changes affecting build procedure
3531
3532    'make check' now detects Rule lines defined but never used.
3533    The NZAQ rules, an instance of this problem, have been removed.
3534
3535  Changes affecting commentary and documentation
3536
3537    Fix Tuesday/Thursday typo in description of time in Israel.
3538    (Thanks to Bert Katz via Pavel Kharitonov and Mike Frysinger.)
3539
3540    Microsoft Windows 8.1 doesn't support tz database names.  (Thanks
3541    to Donald MacQueen.)  Instead, the Microsoft Windows Store app
3542    library supports them.
3543
3544    Add comments about Johnston Island time in the 1960s.
3545    (Thanks to Lyle McElhaney.)
3546
3547    Morocco's 2014 DST start will be as predicted.
3548    (Thanks to Sebastien Willemijns.)
3549
3550
3551Release 2014a - 2014-03-07 23:30:29 -0800
3552
3553  Changes affecting near-future timestamps
3554
3555    Turkey begins DST on 2014-03-31, not 03-30.  (Thanks to Faruk Pasin for
3556    the heads-up, and to Tim Parenti for simplifying the update.)
3557
3558  Changes affecting past timestamps
3559
3560    Fiji ended DST on 2014-01-19 at 02:00, not the previously-scheduled 03:00.
3561    (Thanks to Steffen Thorsen.)
3562
3563    Ukraine switched from Moscow to Eastern European time on 1990-07-01
3564    (not 1992-01-01), and observed DST during the entire next winter.
3565    (Thanks to Vladimir in Moscow via Alois Treindl.)
3566
3567    In 1988 Israel observed DST from 04-10 to 09-04, not 04-09 to 09-03.
3568    (Thanks to Avigdor Finkelstein.)
3569
3570  Changes affecting code
3571
3572    A uninitialized-storage bug in 'localtime' has been fixed.
3573    (Thanks to Logan Chien.)
3574
3575  Changes affecting the build procedure
3576
3577    The settings for 'make check_web' now default to Ubuntu 13.10.
3578
3579  Changes affecting commentary and documentation
3580
3581    The boundary of the US Pacific time zone is given more accurately.
3582    (Thanks to Alan Mintz.)
3583
3584    Chile's 2014 DST will be as predicted.  (Thanks to José Miguel Garrido.)
3585
3586    Paraguay's 2014 DST will be as predicted.  (Thanks to Carlos Raúl Perasso.)
3587
3588    Better descriptions of countries with same time zone history as
3589    Trinidad and Tobago since 1970.  (Thanks to Alan Barrett for suggestion.)
3590
3591    Several changes affect tz-link.htm, the main web page.
3592
3593      Mention Time.is (thanks to Even Scharning) and WX-now (thanks to
3594      David Braverman).
3595
3596      Mention xCal (Internet RFC 6321) and jCal.
3597
3598      Microsoft has some support for tz database names.
3599
3600      CLDR data formats include both XML and JSON.
3601
3602      Mention Maggiolo's map of solar vs standard time.
3603      (Thanks to Arthur David Olson.)
3604
3605      Mention TZ4Net.  (Thanks to Matt Johnson.)
3606
3607      Mention the timezone-olson Haskell package.
3608
3609      Mention zeitverschiebung.net.  (Thanks to Martin Jäger.)
3610
3611      Remove moribund links to daylight-savings-time.info and to
3612      Simple Timer + Clocks.
3613
3614      Update two links.  (Thanks to Oscar van Vlijmen.)
3615
3616      Fix some formatting glitches, e.g., remove random newlines from
3617      abbr elements' title attributes.
3618
3619
3620Release 2013i - 2013-12-17 07:25:23 -0800
3621
3622  Changes affecting near-future timestamps:
3623
3624    Jordan switches back to standard time at 00:00 on December 20, 2013.
3625    The 2006-2011 transition schedule is planned to resume in 2014.
3626    (Thanks to Steffen Thorsen.)
3627
3628  Changes affecting past timestamps:
3629
3630    In 2004, Cuba began DST on March 28, not April 4.
3631    (Thanks to Steffen Thorsen.)
3632
3633  Changes affecting code
3634
3635    The compile-time flag NOSOLAR has been removed, as nowadays the
3636    benefit of slightly shrinking runtime table size is outweighed by the
3637    cost of disallowing potential future updates that exceed old limits.
3638
3639  Changes affecting documentation and commentary
3640
3641    The files solar87, solar88, and solar89 are no longer distributed.
3642    They were a negative experiment - that is, a demonstration that
3643    tz data can represent solar time only with some difficulty and error.
3644    Their presence in the distribution caused confusion, as Riyadh
3645    civil time was generally not solar time in those years.
3646
3647    tz-link.htm now mentions Noda Time.  (Thanks to Matt Johnson.)
3648
3649
3650Release 2013h - 2013-10-25 15:32:32 -0700
3651
3652  Changes affecting current and future timestamps:
3653
3654    Libya has switched its UT offset back to +02 without DST, instead
3655    of +01 with DST.  (Thanks to Even Scharning.)
3656
3657    Western Sahara (Africa/El_Aaiun) uses Morocco's DST rules.
3658    (Thanks to Gwillim Law.)
3659
3660  Changes affecting future timestamps:
3661
3662    Acre and (we guess) western Amazonas will switch from UT -04 to -05
3663    on 2013-11-10.  This affects America/Rio_Branco and America/Eirunepe.
3664    (Thanks to Steffen Thorsen.)
3665
3666    Add entries for DST transitions in Morocco in the year 2038.
3667    This avoids some year-2038 glitches introduced in 2013g.
3668    (Thanks to Yoshito Umaoka for reporting the problem.)
3669
3670  Changes affecting API
3671
3672    The 'tzselect' command no longer requires the 'select' command,
3673    and should now work with /bin/sh on more platforms.  It also works
3674    around a bug in BusyBox awk before version 1.21.0.  (Thanks to
3675    Patrick 'P. J.' McDermott and Alan Barrett.)
3676
3677  Changes affecting code
3678
3679    Fix localtime overflow bugs with 32-bit unsigned time_t.
3680
3681    zdump no longer assumes sscanf returns maximal values on overflow.
3682
3683  Changes affecting the build procedure
3684
3685    The builder can specify which programs to use, if any, instead of
3686    'ar' and 'ranlib', and libtz.a is now built locally before being
3687    installed.  (Thanks to Michael Forney.)
3688
3689    A dependency typo in the 'zdump' rule has been fixed.
3690    (Thanks to Andrew Paprocki.)
3691
3692    The Makefile has been simplified by assuming that 'mkdir -p' and 'cp -f'
3693    work as specified by POSIX.2-1992 or later; this is portable nowadays.
3694
3695    'make clean' no longer removes 'leapseconds', since it's
3696    host-independent and is part of the distribution.
3697
3698    The unused makefile macros TZCSRCS, TZDSRCS, DATESRCS have been removed.
3699
3700  Changes affecting documentation and commentary
3701
3702    tz-link.htm now mentions TC TIMEZONE's draft time zone service protocol
3703    (thanks to Mike Douglass) and TimezoneJS.Date (thanks to Jim Fehrle).
3704
3705    Update URLs in tz-link page.  Add URLs for Microsoft Windows, since
3706    8.1 introduces tz support.  Remove URLs for Tru64 and UnixWare (no
3707    longer maintained) and for old advisories.  SOFA now does C.
3708
3709Release 2013g - 2013-09-30 21:08:26 -0700
3710
3711  Changes affecting current and near-future timestamps
3712
3713    Morocco now observes DST from the last Sunday in March to the last
3714    Sunday in October, not April to September respectively.  (Thanks
3715    to Steffen Thorsen.)
3716
3717  Changes affecting 'zic'
3718
3719    'zic' now runs on platforms that lack both hard links and symlinks.
3720    (Thanks to Theo Veenker for reporting the problem, for MinGW.)
3721    Also, fix some bugs on platforms that lack hard links but have symlinks.
3722
3723    'zic -v' again warns that Asia/Tehran has no POSIX environment variable
3724    to predict the far future, fixing a bug introduced in 2013e.
3725
3726  Changes affecting the build procedure
3727
3728    The 'leapseconds' file is again put into the tzdata tarball.
3729    Also, 'leapseconds.awk', so tzdata is self-contained.  (Thanks to
3730    Matt Burgess and Ian Abbott.)  The timestamps of these and other
3731    dependent files in tarballs are adjusted more consistently.
3732
3733  Changes affecting documentation and commentary
3734
3735    The README file is now part of the data tarball as well as the code.
3736    It now states that files are public domain unless otherwise specified.
3737    (Thanks to Andrew Main (Zefram) for asking for clarifications.)
3738    Its details about the 1989 release moved to a place of honor near
3739    the end of NEWS.
3740
3741
3742Release 2013f - 2013-09-24 23:37:36 -0700
3743
3744  Changes affecting near-future timestamps
3745
3746    Tocantins will very likely not observe DST starting this spring.
3747    (Thanks to Steffen Thorsen.)
3748
3749    Jordan will likely stay at UT +03 indefinitely, and will not fall
3750    back this fall.
3751
3752    Palestine will fall back at 00:00, not 01:00.  (Thanks to Steffen Thorsen.)
3753
3754  Changes affecting API
3755
3756    The types of the global variables 'timezone' and 'altzone' (if present)
3757    have been changed back to 'long'.  This is required for 'timezone'
3758    by POSIX, and for 'altzone' by common practice, e.g., Solaris 11.
3759    These variables were originally 'long' in the tz code, but were
3760    mistakenly changed to 'time_t' in 1987; nobody reported the
3761    incompatibility until now.  The difference matters on x32, where
3762    'long' is 32 bits and 'time_t' is 64.  (Thanks to Elliott Hughes.)
3763
3764  Changes affecting the build procedure
3765
3766    Avoid long strings in leapseconds.awk to work around a mawk bug.
3767    (Thanks to Cyril Baurand.)
3768
3769  Changes affecting documentation and commentary
3770
3771    New file 'NEWS' that contains release notes like this one.
3772
3773    Paraguay's law does not specify DST transition time; 00:00 is customary.
3774    (Thanks to Waldemar Villamayor-Venialbo.)
3775
3776    Minor capitalization fixes.
3777
3778  Changes affecting version-control only
3779
3780    The experimental GitHub repository now contains annotated and
3781    signed tags for recent releases, e.g., '2013e' for Release 2013e.
3782    Releases are tagged starting with 2012e; earlier releases were
3783    done differently, and tags would either not have a simple name or
3784    not exactly match what was released.
3785
3786    'make set-timestamps' is now simpler and a bit more portable.
3787
3788
3789Release 2013e - 2013-09-19 23:50:04 -0700
3790
3791  Changes affecting near-future timestamps
3792
3793    This year Fiji will start DST on October 27, not October 20.
3794    (Thanks to David Wheeler for the heads-up.)  For now, guess that
3795    Fiji will continue to spring forward the Sunday before the fourth
3796    Monday in October.
3797
3798  Changes affecting current and future time zone abbreviations
3799
3800    Use WIB/WITA/WIT rather than WIT/CIT/EIT for alphabetic Indonesian
3801    time zone abbreviations since 1932.  (Thanks to George Ziegler,
3802    Priyadi Iman Nurcahyo, Zakaria, Jason Grimes, Martin Pitt, and
3803    Benny Lin.)  This affects Asia/Dili, Asia/Jakarta, Asia/Jayapura,
3804    Asia/Makassar, and Asia/Pontianak.
3805
3806    Use ART (UT -03, standard time), rather than WARST (also -03, but
3807    daylight saving time) for San Luis, Argentina since 2009.
3808
3809  Changes affecting Godthåb timestamps after 2037 if version mismatch
3810
3811    Allow POSIX-like TZ strings where the transition time's hour can
3812    range from -167 through 167, instead of the POSIX-required 0
3813    through 24.  E.g., TZ='FJT-12FJST,M10.3.1/146,M1.3.4/75' for the
3814    new Fiji rules.  This is a more-compact way to represent
3815    far-future timestamps for America/Godthab, America/Santiago,
3816    Antarctica/Palmer, Asia/Gaza, Asia/Hebron, Asia/Jerusalem,
3817    Pacific/Easter, and Pacific/Fiji.  Other zones are unaffected by
3818    this change.  (Derived from a suggestion by Arthur David Olson.)
3819
3820    Allow POSIX-like TZ strings where daylight saving time is in
3821    effect all year.  E.g., TZ='WART4WARST,J1/0,J365/25' for Western
3822    Argentina Summer Time all year.  This supports a more-compact way
3823    to represent the 2013d data for America/Argentina/San_Luis.
3824    Because of the change for San Luis noted above this change does not
3825    affect the current data.  (Thanks to Andrew Main (Zefram) for
3826    suggestions that improved this change.)
3827
3828    Where these two TZ changes take effect, there is a minor extension
3829    to the tz file format in that it allows new values for the
3830    embedded TZ-format string, and the tz file format version number
3831    has therefore been increased from 2 to 3 as a precaution.
3832    Version-2-based client code should continue to work as before for
3833    all timestamps before 2038.  Existing version-2-based client code
3834    (tzcode, GNU/Linux, Solaris) has been tested on version-3-format
3835    files, and typically works in practice even for timestamps after
3836    2037; the only known exception is America/Godthab.
3837
3838  Changes affecting timestamps before 1970
3839
3840    Pacific/Johnston is now a link to Pacific/Honolulu.  This corrects
3841    some errors before 1947.
3842
3843    Some zones have been turned into links, when they differ from existing
3844    zones only in older data entries that were likely invented or that
3845    differ only in LMT or transitions from LMT.  These changes affect
3846    only timestamps before 1943.  The affected zones are:
3847    Africa/Juba, America/Anguilla, America/Aruba, America/Dominica,
3848    America/Grenada, America/Guadeloupe, America/Marigot,
3849    America/Montserrat, America/St_Barthelemy, America/St_Kitts,
3850    America/St_Lucia, America/St_Thomas, America/St_Vincent,
3851    America/Tortola, and Europe/Vaduz.  (Thanks to Alois Treindl for
3852    confirming that the old Europe/Vaduz zone was wrong and the new
3853    link is better for WWII-era times.)
3854
3855    Change Kingston Mean Time from -5:07:12 to -5:07:11.  This affects
3856    America/Cayman, America/Jamaica and America/Grand_Turk timestamps
3857    from 1890 to 1912.
3858
3859    Change the UT offset of Bern Mean Time from 0:29:44 to 0:29:46.
3860    This affects Europe/Zurich timestamps from 1853 to 1894.  (Thanks
3861    to Alois Treindl.)
3862
3863    Change the date of the circa-1850 Zurich transition from 1849-09-12
3864    to 1853-07-16, overriding Shanks with data from Messerli about
3865    postal and telegraph time in Switzerland.
3866
3867  Changes affecting time zone abbreviations before 1970
3868
3869    For Asia/Jakarta, use BMT (not JMT) for mean time from 1923 to 1932,
3870    as Jakarta was called Batavia back then.
3871
3872  Changes affecting API
3873
3874    The 'zic' command now outputs a dummy transition when far-future
3875    data can't be summarized using a TZ string, and uses a 402-year
3876    window rather than a 400-year window.  For the current data, this
3877    affects only the Asia/Tehran file.  It does not affect any of the
3878    timestamps that this file represents, so zdump outputs the same
3879    information as before.  (Thanks to Andrew Main (Zefram).)
3880
3881    The 'date' command has a new '-r' option, which lets you specify
3882    the integer time to display, a la FreeBSD.
3883
3884    The 'tzselect' command has two new options '-c' and '-n', which lets you
3885    select a zone based on latitude and longitude.
3886
3887    The 'zic' command's '-v' option now warns about constructs that
3888    require the new version-3 binary file format.  (Thanks to Arthur
3889    David Olson for the suggestion.)
3890
3891    Support for floating-point time_t has been removed.
3892    It was always dicey, and POSIX no longer requires it.
3893    (Thanks to Eric Blake for suggesting to the POSIX committee to
3894    remove it, and thanks to Alan Barrett, Clive D.W. Feather, Andy
3895    Heninger, Arthur David Olson, and Alois Treindl, for reporting
3896    bugs and elucidating some of the corners of the old floating-point
3897    implementation.)
3898
3899    The signatures of 'offtime', 'timeoff', and 'gtime' have been
3900    changed back to the old practice of using 'long' to represent UT
3901    offsets.  This had been inadvertently and mistakenly changed to
3902    'int_fast32_t'.  (Thanks to Christos Zoulas.)
3903
3904    The code avoids undefined behavior on integer overflow in some
3905    more places, including gmtime, localtime, mktime and zdump.
3906
3907  Changes affecting the zdump utility
3908
3909    zdump now outputs "UT" when referring to Universal Time, not "UTC".
3910    "UTC" does not make sense for timestamps that predate the introduction
3911    of UTC, whereas "UT", a more-generic term, does.  (Thanks to Steve Allen
3912    for clarifying UT vs UTC.)
3913
3914  Data changes affecting behavior of tzselect and similar programs
3915
3916    Country code BQ is now called the more-common name "Caribbean Netherlands"
3917    rather than the more-official "Bonaire, St Eustatius & Saba".
3918
3919    Remove from zone.tab the names America/Montreal, America/Shiprock,
3920    and Antarctica/South_Pole, as they are equivalent to existing
3921    same-country-code zones for post-1970 timestamps.  The data entries for
3922    these names are unchanged, so the names continue to work as before.
3923
3924  Changes affecting code internals
3925
3926    zic -c now runs way faster on 64-bit hosts when given large numbers.
3927
3928    zic now uses vfprintf to avoid allocating and freeing some memory.
3929
3930    tzselect now computes the list of continents from the data,
3931    rather than have it hard-coded.
3932
3933    Minor changes pacify GCC 4.7.3 and GCC 4.8.1.
3934
3935  Changes affecting the build procedure
3936
3937    The 'leapseconds' file is now generated automatically from a
3938    new file 'leap-seconds.list', which is a copy of
3939    <ftp://ftp.nist.gov/pub/time/leap-seconds.list>
3940    A new source file 'leapseconds.awk' implements this.
3941    The goal is simplification of the future maintenance of 'leapseconds'.
3942
3943    When building the 'posix' or 'right' subdirectories, if the
3944    subdirectory would be a copy of the default subdirectory, it is
3945    now made a symbolic link if that is supported.  This saves about
3946    2 MB of file system space.
3947
3948    The links America/Shiprock and Antarctica/South_Pole have been
3949    moved to the 'backward' file.  This affects only nondefault builds
3950    that omit 'backward'.
3951
3952  Changes affecting version-control only
3953
3954    .gitignore now ignores 'date'.
3955
3956  Changes affecting documentation and commentary
3957
3958    Changes to the 'tzfile' man page
3959
3960      It now mentions that the binary file format may be extended in
3961      future versions by appending data.
3962
3963      It now refers to the 'zdump' and 'zic' man pages.
3964
3965    Changes to the 'zic' man page
3966
3967      It lists conditions that elicit a warning with '-v'.
3968
3969      It says that the behavior is unspecified when duplicate names
3970      are given, or if the source of one link is the target of another.
3971
3972      Its examples are updated to match the latest data.
3973
3974      The definition of white space has been clarified slightly.
3975      (Thanks to Michael Deckers.)
3976
3977    Changes to the 'Theory' file
3978
3979      There is a new section about the accuracy of the tz database,
3980      describing the many ways that errors can creep in, and
3981      explaining why so many of the pre-1970 timestamps are wrong or
3982      misleading (thanks to Steve Allen, Lester Caine, and Garrett
3983      Wollman for discussions that contributed to this).
3984
3985      The 'Theory' file describes LMT better (this follows a
3986      suggestion by Guy Harris).
3987
3988      It refers to the 2013 edition of POSIX rather than the 2004 edition.
3989
3990      It's mentioned that excluding 'backward' should not affect the
3991      other data, and it suggests at least one zone.tab name per
3992      inhabited country (thanks to Stephen Colebourne).
3993
3994      Some longstanding restrictions on names are documented, e.g.,
3995      'America/New_York' precludes 'America/New_York/Bronx'.
3996
3997      It gives more reasons for the 1970 cutoff.
3998
3999      It now mentions which time_t variants are supported, such as
4000      signed integer time_t.  (Thanks to Paul Goyette for reporting
4001      typos in an experimental version of this change.)
4002
4003      (Thanks to Philip Newton for correcting typos in these changes.)
4004
4005    Documentation and commentary is more careful to distinguish UT in
4006    general from UTC in particular.  (Thanks to Steve Allen.)
4007
4008    Add a better source for the Zurich 1894 transition.
4009    (Thanks to Pierre-Yves Berger.)
4010
4011    Update shapefile citations in tz-link.htm.  (Thanks to Guy Harris.)
4012
4013
4014Release 2013d - 2013-07-05 07:38:01 -0700
4015
4016  Changes affecting future timestamps:
4017
4018    Morocco's midsummer transitions this year are July 7 and August 10,
4019    not July 9 and August 8.  (Thanks to Andrew Paprocki.)
4020
4021    Israel now falls back on the last Sunday of October.
4022    (Thanks to Ephraim Silverberg.)
4023
4024  Changes affecting past timestamps:
4025
4026    Specify Jerusalem's location more precisely; this changes the pre-1880
4027    times by 2 s.
4028
4029  Changing affecting metadata only:
4030
4031    Fix typos in the entries for country codes BQ and SX.
4032
4033  Changes affecting code:
4034
4035    Rework the code to fix a bug with handling Australia/Macquarie on
4036    32-bit hosts (thanks to Arthur David Olson).
4037
4038    Port to platforms like NetBSD, where time_t can be wider than long.
4039
4040    Add support for testing time_t types other than the system's.
4041    Run 'make check_time_t_alternatives' to try this out.
4042    Currently, the tests fail for unsigned time_t;
4043    this should get fixed at some point.
4044
4045  Changes affecting documentation and commentary:
4046
4047    Deemphasize the significance of national borders.
4048
4049    Update the zdump man page.
4050
4051    Remove obsolete NOID comment (thanks to Denis Excoffier).
4052
4053    Update several URLs and comments in the web pages.
4054
4055    Spelling fixes (thanks to Kevin Lyda and Jonathan Leffler).
4056
4057    Update URL for CLDR Zone->Tzid table (thanks to Yoshito Umaoka).
4058
4059
4060Release 2013c - 2013-04-19 16:17:40 -0700
4061
4062  Changes affecting current and future timestamps:
4063
4064    Palestine observed DST starting March 29, 2013.  (Thanks to
4065    Steffen Thorsen.)  From 2013 on, Gaza and Hebron both observe DST,
4066    with the predicted rules being the last Thursday in March at 24:00
4067    to the first Friday on or after September 21 at 01:00.
4068
4069    Assume that the recent change to Paraguay's DST rules is permanent,
4070    by moving the end of DST to the 4th Sunday in March every year.
4071    (Thanks to Carlos Raúl Perasso.)
4072
4073  Changes affecting past timestamps:
4074
4075    Fix some historical data for Palestine to agree with that of
4076    timeanddate.com, as follows:
4077
4078	  The spring 2008 change in Gaza and Hebron was on 00:00 Mar 28, not
4079	  00:00 Apr 1.
4080
4081	  The fall 2009 change in Gaza and Hebron on Sep 4 was at 01:00, not
4082	  02:00.
4083
4084	  The spring 2010 change in Hebron was 00:00 Mar 26, not 00:01 Mar 27.
4085
4086	  The spring 2011 change in Gaza was 00:01 Apr 1, not 12:01 Apr 2.
4087
4088	  The spring 2011 change in Hebron on Apr 1 was at 00:01, not 12:01.
4089
4090	  The fall 2011 change in Hebron on Sep 30 was at 00:00, not 03:00.
4091
4092    Fix times of habitation for Macquarie to agree with the Tasmania
4093    Parks & Wildlife Service history, which indicates that permanent
4094    habitation was 1899-1919 and 1948 on.
4095
4096  Changing affecting metadata only:
4097
4098    Macquarie Island is politically part of Australia, not Antarctica.
4099    (Thanks to Tobias Conradi.)
4100
4101    Sort Macquarie more-consistently with other parts of Australia.
4102    (Thanks to Tim Parenti.)
4103
4104
4105Release 2013b - 2013-03-10 22:33:40 -0700
4106
4107  Changes affecting current and future timestamps:
4108
4109    Haiti uses US daylight-saving rules this year, and presumably future years.
4110    This changes timestamps starting today.  (Thanks to Steffen Thorsen.)
4111
4112    Paraguay will end DST on March 24 this year.
4113    (Thanks to Steffen Thorsen.)  For now, assume it's just this year.
4114
4115    Morocco does not observe DST during Ramadan;
4116    try to predict Ramadan in Morocco as best we can.
4117    (Thanks to Erik Homoet for the heads-up.)
4118
4119  Changes affecting commentary:
4120
4121    Update URLs in tz-link page.  Add URLs for webOS, BB10, iOS.
4122    Update URL for Solaris.  Mention Internet RFC 6557.
4123    Update Internet RFCs 2445->5545, 2822->5322.
4124    Switch from FTP to HTTP for Internet RFCs.
4125
4126
4127Release 2013a - 2013-02-27 09:20:35 -0800
4128
4129  Change affecting binary data format:
4130
4131    The zone offset at the end of version-2-format zone files is now
4132    allowed to be 24:00, as per POSIX.1-2008.  (Thanks to Arthur David Olson.)
4133
4134  Changes affecting current and future timestamps:
4135
4136    Chile's 2013 rules, and we guess rules for 2014 and later, will be
4137    the same as 2012, namely Apr Sun>=23 03:00 UTC to Sep Sun>=2 04:00 UTC.
4138    (Thanks to Steffen Thorsen and Robert Elz.)
4139
4140    New Zones Asia/Khandyga, Asia/Ust-Nera, Europe/Busingen.
4141    (Thanks to Tobias Conradi and Arthur David Olson.)
4142
4143  Many changes affect historical timestamps before 1940.
4144  These were deduced from: Milne J. Civil time. Geogr J. 1899
4145  Feb;13(2):173-94 <https://www.jstor.org/stable/1774359>.
4146
4147  Changes affecting the code:
4148
4149    Fix zic bug that mishandled Egypt's 2010 changes (this also affected
4150    the data).  (Thanks to Arthur David Olson.)
4151
4152    Fix localtime bug when time_t is unsigned and data files were generated
4153    by a signed time_t system.  (Thanks to Doug Bailey for reporting and
4154    to Arthur David Olson for fixing.)
4155
4156    Allow the email address for bug reports to be set by the packager.
4157    The default is tz@iana.org, as before.  (Thanks to Joseph S. Myers.)
4158
4159    Update HTML checking to be compatible with Ubuntu 12.10.
4160
4161    Check that files are a safe subset of ASCII.  At some point we may
4162    relax this requirement to a safe subset of UTF-8.  Without the
4163    check, some non-UTF-8 encodings were leaking into the distribution.
4164
4165  Commentary changes:
4166
4167    Restore a comment about copyright notices that was inadvertently deleted.
4168    (Thanks to Arthur David Olson.)
4169
4170    Improve the commentary about which districts observe what times
4171    in Russia.  (Thanks to Oscar van Vlijmen and Arthur David Olson.)
4172
4173    Add web page links to tz.js.
4174
4175    Add "Run by the Monkeys" to tz-art.  (Thanks to Arthur David Olson.)
4176
4177
4178Release 2012j - 2012-11-12 18:34:49 -0800
4179
4180  Libya moved to CET this weekend, but with DST planned next year.
4181  (Thanks to Even Scharning, Steffen Thorsen, and Tim Parenti.)
4182
4183  Signatures now have the extension .asc, not .sign, as that's more
4184  standard.  (Thanks to Phil Pennock.)
4185
4186  The output of 'zdump --version', and of 'zic --version', now
4187  uses a format that is more typical for --version.
4188  (Thanks to Joseph S. Myers.)
4189
4190  The output of 'tzselect --help', 'zdump --help', and 'zic --help'
4191  now uses tz@iana.org rather than the old elsie address.
4192
4193  zic -v now complains about abbreviations that are less than 3
4194  or more than 6 characters, as per Posix.  Formerly, it checked
4195  for abbreviations that were more than 3.
4196
4197  'make public' no longer puts its temporary directory under /tmp,
4198  and uses the just-built zic rather than the system zic.
4199
4200  Various fixes to documentation and commentary.
4201
4202
4203Release 2012i - 2012-11-03 12:57:09 -0700
4204
4205  Cuba switches from DST tomorrow at 01:00.  (Thanks to Steffen Thorsen.)
4206
4207  Linker flags can now be specified via LDFLAGS.
4208  AWK now defaults to 'awk', not 'nawk'.
4209  The shell in tzselect now defaults to /bin/bash, but this can
4210  be overridden by specifying KSHELL.
4211  The main web page now mentions the unofficial GitHub repository.
4212  (Thanks to Mike Frysinger.)
4213
4214  Tarball signatures can now be built by running 'make signatures'.
4215  There are also new makefile rules 'tarballs', 'check_public', and
4216  separate makefile rules for each tarball and signature file.
4217  A few makefile rules are now more portable to strict POSIX.
4218
4219  The main web page now lists the canonical IANA URL.
4220
4221
4222Release 2012h - 2012-10-26 22:49:10 -0700
4223
4224  Bahia no longer has DST.  (Thanks to Kelley Cook.)
4225
4226  Tocantins has DST.  (Thanks to Rodrigo Severo.)
4227
4228  Israel has new DST rules next year.  (Thanks to Ephraim Silverberg.)
4229
4230  Jordan stays on DST this winter.  (Thanks to Steffen Thorsen.)
4231
4232  Web page updates.
4233
4234  More C modernization, except that at Arthur David Olson's suggestion
4235  the instances of 'register' were kept.
4236
4237
4238Release 2012g - 2012-10-17 20:59:45 -0700
4239
4240  Samoa fall 2012 and later.  (Thanks to Nicholas Pereira and Robert Elz.)
4241
4242  Palestine fall 2012.  (Thanks to Steffen Thorsen.)
4243
4244  Assume C89.
4245
4246  To attack the version-number problem, this release ships the file
4247  'Makefile' (which contains the release number) in both the tzcode and
4248  the tzdata tarballs.  The two Makefiles are identical, and should be
4249  identical in any matching pair of tarballs, so it shouldn't matter
4250  which order you extract the tarballs.  Perhaps we can come up with a
4251  better version-number scheme at some point; this scheme does have the
4252  virtue of not adding more files.
4253
4254
4255Release 2012f - 2012-09-12 23:17:03 -0700
4256
4257  * australasia (Pacific/Fiji): Fiji DST is October 21 through January
4258    20 this year.  (Thanks to Steffen Thorsen.)
4259
4260
4261Release 2012e - 2012-08-02 20:44:55 -0700
4262
4263  * australasia (Pacific/Fakaofo): Tokelau is UT +13, not +14.
4264    (Thanks to Steffen Thorsen.)
4265
4266  * Use a single version number for both code and data.
4267
4268  * .gitignore: New file.
4269
4270  * Remove trailing white space.
4271
4272
4273Release code2012c-data2012d - 2012-07-19 16:35:33 -0700
4274
4275  Changes for Morocco's timestamps, which take effect in a couple of
4276  hours, along with infrastructure changes to accommodate how the tz
4277  code and data are released on IANA.
4278
4279
4280Release data2012c - 2012-03-27 12:17:25 -0400
4281
4282  africa
4283	Summer time changes for Morocco (to start late April 2012)
4284
4285  asia
4286	Changes for 2012 for Gaza & the West Bank (Hebron) and Syria
4287
4288  northamerica
4289	Haiti following US/Canada rules for 2012 (and we're assuming,
4290	for now anyway, for the future).
4291
4292
4293Release 2012b - 2012-03-02 12:29:15 +0700
4294
4295  There is just one change to tzcode2012b (compared with 2012a):
4296  the Makefile that was accidentally included with 2012a has been
4297  replaced with the version that should have been there, which is
4298  identical with the previous version (from tzcode2011i).
4299
4300  There are just two changes in tzdata2012b compared with 2012a.
4301
4302  Most significantly, summer time in Cuba has been delayed 3 weeks
4303  (now starts April 1 rather than March 11).   Since Mar 11 (the old start
4304  date, as listed in 2012a) is just a little over a week away, this
4305  change is urgent.
4306
4307  Less importantly, an excess tab in one of the changes in zone.tab
4308  in 2012a has been removed.
4309
4310
4311Release 2012a - 2012-03-01 18:28:10 +0700
4312
4313  The changes in tzcode2012a (compared to the previous version, 2011i)
4314  are entirely to the README and tz-art.htm and tz-link.htm files, if
4315  none of those concern you, you can ignore the code update.  The changes
4316  reflect the changed addresses for the mailing list and the code and
4317  data distribution points & methods (and a link to DateTime::TimeZone::Tzfile
4318  has been added to tz-link.htm).
4319
4320  In tzdata2012a (compared to the previous release, which was 2011n)
4321  the major changes are:
4322	Chile 2011/2012 and 2012/2013 summer time date adjustments.
4323	Falkland Islands onto permanent summer time (we're assuming for the
4324		foreseeable future, though 2012 is all we're fairly certain of.)
4325	Armenia has abolished Summer Time.
4326	Tokelau jumped the International Date Line back last December
4327		(just the same as their near neighbour, Samoa).
4328	America/Creston is a new zone for a small area of British Columbia
4329	There will be a leapsecond 2012-06-30 23:59:60 UTC.
4330
4331  Other minor changes are:
4332	Corrections to 1918 Canadian summer time end dates.
4333	Updated URL for UK time zone history (in comments)
4334	A few typos in Le Corre's list of free French place names (comments)
4335
4336
4337Release data2011n - 2011-10-30 14:57:54 +0700
4338
4339  There are three changes of note - most urgently, Cuba (America/Havana)
4340  has extended summer time by two weeks, now to end on Nov 13, rather than
4341  the (already past) Oct 30.   Second, the Pridnestrovian Moldavian Republic
4342  (Europe/Tiraspol) decided not to split from the rest of Moldova after
4343  all, and consequently that zone has been removed (again) and reinstated
4344  in the "backward" file as a link to Europe/Chisinau.   And third, the
4345  end date for Fiji's summer time this summer was moved forward from the
4346  earlier planned Feb 26, to Jan 22.
4347
4348  Apart from that, Moldova (MD) returns to a single entry in zone.tab
4349  (and the incorrect syntax that was in the 2011m version of that file
4350  is so fixed - it would have been fixed in a different way had this
4351  change not happened - that's the "missing" sccs version id).
4352
4353
4354Release data2011m - 2011-10-24 21:42:16 +0700
4355
4356  In particular, the typos in comments in the data (2011-11-17 should have
4357  been 2011-10-17 as Alan Barrett noted, and spelling of Tiraspol that
4358  Tim Parenti noted) have been fixed, and the change for Ukraine has been
4359  made in all 4 Ukrainian zones, rather than just Kiev (again, thanks to
4360  Tim Parenti, and also Denys Gavrysh)
4361
4362  In addition, I added Europe/Tiraspol to zone.tab.
4363
4364  This time, all the files have new version numbers...  (including the files
4365  otherwise unchanged in 2011m that were changed in 2011l but didn't get new
4366  version numbers there...)
4367
4368
4369Release data2011l - 2011-10-10 11:15:43 +0700
4370
4371  There are just 2 changes that cause different generated tzdata files from
4372  zic, to Asia/Hebron and Pacific/Fiji - the possible change for Bahia, Brazil
4373  is included, but commented out.  Compared with the diff I sent out last week,
4374  this version also includes attributions for the sources for the changes
4375  (in much the same format as ado used, but the html tags have not been
4376  checked, verified, or used in any way at all, so if there are errors there,
4377  please let me know.)
4378
4379
4380Release data2011k - 2011-09-20 17:54:03 -0400
4381
4382  [not summarized]
4383
4384
4385Release data2011j - 2011-09-12 09:22:49 -0400
4386
4387  (contemporary changes for Samoa; past changes for Kenya, Uganda, and
4388  Tanzania); there are also two spelling corrections to comments in
4389  the australasia file (with thanks to Christos Zoulas).
4390
4391
4392Release 2011i - 2011-08-29 05:56:32 -0400
4393
4394  [not summarized]
4395
4396
4397Release data2011h - 2011-06-15 18:41:48 -0400
4398
4399  Russia and Curaçao changes
4400
4401
4402Release 2011g - 2011-04-25 09:07:22 -0400
4403
4404  update the rules for Egypt to reflect its abandonment of DST this year
4405
4406
4407Release 2011f - 2011-04-06 17:14:53 -0400
4408
4409  [not summarized]
4410
4411
4412Release 2011e - 2011-03-31 16:04:38 -0400
4413
4414  Morocco, Chile, and tz-link changes
4415
4416
4417Release 2011d - 2011-03-14 09:18:01 -0400
4418
4419  changes that impact present-day timestamps in Cuba, Samoa, and Turkey
4420
4421
4422Release 2011c - 2011-03-07 09:30:09 -0500
4423
4424  These do affect current timestamps in Chile and Annette Island, Canada.
4425
4426
4427Release 2011b - 2011-02-07 08:44:50 -0500
4428
4429  [not summarized]
4430
4431
4432Release 2011a - 2011-01-24 10:30:16 -0500
4433
4434  [not summarized]
4435
4436
4437Release data2010o - 2010-11-01 09:18:23 -0400
4438
4439  change to the end of DST in Fiji in 2011
4440
4441
4442Release 2010n - 2010-10-25 08:19:17 -0400
4443
4444  [not summarized]
4445
4446
4447Release 2010m - 2010-09-27 09:24:48 -0400
4448
4449  Hong Kong, Vostok, and zic.c changes
4450
4451
4452Release 2010l - 2010-08-16 06:57:25 -0400
4453
4454  [not summarized]
4455
4456
4457Release 2010k - 2010-07-26 10:42:27 -0400
4458
4459  [not summarized]
4460
4461
4462Release 2010j - 2010-05-10 09:07:48 -0400
4463
4464  changes for Bahía de Banderas and for version naming
4465
4466
4467Release data2010i - 2010-04-16 18:50:45 -0400
4468
4469  the end of DST in Morocco on 2010-08-08
4470
4471
4472Release data2010h - 2010-04-05 09:58:56 -0400
4473
4474  [not summarized]
4475
4476
4477Release data2010g - 2010-03-24 11:14:53 -0400
4478
4479  [not summarized]
4480
4481
4482Release 2010f - 2010-03-22 09:45:46 -0400
4483
4484  [not summarized]
4485
4486
4487Release data2010e - 2010-03-08 14:24:27 -0500
4488
4489  corrects the Dhaka bug found by Danvin Ruangchan
4490
4491
4492Release data2010d - 2010-03-06 07:26:01 -0500
4493
4494  [not summarized]
4495
4496
4497Release 2010c - 2010-03-01 09:20:58 -0500
4498
4499  changes including KRE's suggestion for earlier initialization of
4500  "goahead" and "goback" structure elements
4501
4502
4503Release code2010a - 2010-02-16 10:40:04 -0500
4504
4505  [not summarized]
4506
4507
4508Release data2010b - 2010-01-20 12:37:01 -0500
4509
4510  Mexico changes
4511
4512
4513Release data2010a - 2010-01-18 08:30:04 -0500
4514
4515  changes to Dhaka
4516
4517
4518Release data2009u - 2009-12-26 08:32:28 -0500
4519
4520  changes to DST in Bangladesh
4521
4522
4523Release 2009t - 2009-12-21 13:24:27 -0500
4524
4525  [not summarized]
4526
4527
4528Release data2009s - 2009-11-14 10:26:32 -0500
4529
4530  (cosmetic) Antarctica change and the DST-in-Fiji-in-2009-and-2010 change
4531
4532
4533Release 2009r - 2009-11-09 10:10:31 -0500
4534
4535  "antarctica" and "tz-link.htm" changes
4536
4537
4538Release 2009q - 2009-11-02 09:12:40 -0500
4539
4540  with two corrections as reported by Eric Muller and Philip Newton
4541
4542
4543Release data2009p - 2009-10-23 15:05:27 -0400
4544
4545  Argentina (including San Luis) changes (with the correction from
4546  Mariano Absatz)
4547
4548
4549Release data2009o - 2009-10-14 16:49:38 -0400
4550
4551  Samoa (commentary only), Pakistan, and Bangladesh changes
4552
4553
4554Release data2009n - 2009-09-22 15:13:38 -0400
4555
4556  added commentary for Argentina and a change to the end of DST in
4557  2009 in Pakistan
4558
4559
4560Release data2009m - 2009-09-03 10:23:43 -0400
4561
4562  Samoa and Palestine changes
4563
4564
4565Release data2009l - 2009-08-14 09:13:07 -0400
4566
4567  Samoa (comments only) and Egypt
4568
4569
4570Release 2009k - 2009-07-20 09:46:08 -0400
4571
4572  [not summarized]
4573
4574
4575Release data2009j - 2009-06-15 06:43:59 -0400
4576
4577  Bangladesh change (with a short turnaround since the DST change is
4578  impending)
4579
4580
4581Release 2009i - 2009-06-08 09:21:22 -0400
4582
4583  updating for DST in Bangladesh this year
4584
4585
4586Release 2009h - 2009-05-26 09:19:14 -0400
4587
4588  [not summarized]
4589
4590
4591Release data2009g - 2009-04-20 16:34:07 -0400
4592
4593  Cairo
4594
4595
4596Release data2009f - 2009-04-10 11:00:52 -0400
4597
4598  correct DST in Pakistan
4599
4600
4601Release 2009e - 2009-04-06 09:08:11 -0400
4602
4603  [not summarized]
4604
4605
4606Release 2009d - 2009-03-23 09:38:12 -0400
4607
4608  Morocco, Tunisia, Argentina, and American Astronomical Society changes
4609
4610
4611Release data2009c - 2009-03-16 09:47:51 -0400
4612
4613  change to the start of Cuban DST
4614
4615
4616Release 2009b - 2009-02-09 11:15:22 -0500
4617
4618  [not summarized]
4619
4620
4621Release 2009a - 2009-01-21 10:09:39 -0500
4622
4623  [not summarized]
4624
4625
4626Release data2008i - 2008-10-21 12:10:25 -0400
4627
4628  southamerica and zone.tab files, with Argentina DST rule changes and
4629  United States zone reordering and recommenting
4630
4631
4632Release 2008h - 2008-10-13 07:33:56 -0400
4633
4634  [not summarized]
4635
4636
4637Release 2008g - 2008-10-06 09:03:18 -0400
4638
4639  Fix a broken HTML anchor and update Brazil's DST transitions;
4640  there's also a slight reordering of information in tz-art.htm.
4641
4642
4643Release data2008f - 2008-09-09 22:33:26 -0400
4644
4645  [not summarized]
4646
4647
4648Release 2008e - 2008-07-28 14:11:17 -0400
4649
4650  changes by Arthur David Olson and Jesper Nørgaard Welen
4651
4652
4653Release data2008d - 2008-07-07 09:51:38 -0400
4654
4655  changes by Arthur David Olson, Paul Eggert, and Rodrigo Severo
4656
4657
4658Release data2008c - 2008-05-19 17:48:03 -0400
4659
4660  Pakistan, Morocco, and Mongolia
4661
4662
4663Release data2008b - 2008-03-24 08:30:59 -0400
4664
4665  including renaming Asia/Calcutta to Asia/Kolkata, with a backward
4666  link provided
4667
4668
4669Release 2008a - 2008-03-08 05:42:16 -0500
4670
4671  [not summarized]
4672
4673
4674Release 2007k - 2007-12-31 10:25:22 -0500
4675
4676  most importantly, changes to the "southamerica" file based on
4677  Argentina's readoption of daylight saving time
4678
4679
4680Release 2007j - 2007-12-03 09:51:01 -0500
4681
4682  1. eliminate the "P" (parameter) macro;
4683
4684  2. the "noncontroversial" changes circulated on the time zone
4685  mailing list (less the changes to "logwtmp.c");
4686
4687  3. eliminate "too many transition" errors when "min" is used in time
4688  zone rules;
4689
4690  4. changes by Paul Eggert (including updated information for Venezuela).
4691
4692
4693Release data2007i - 2007-10-30 10:28:11 -0400
4694
4695  changes for Cuba and Syria
4696
4697
4698Release 2007h - 2007-10-01 10:05:51 -0400
4699
4700  changes by Paul Eggert, as well as an updated link to the ICU
4701  project in tz-link.htm
4702
4703
4704Release 2007g - 2007-08-20 10:47:59 -0400
4705
4706  changes by Paul Eggert
4707
4708  The "leapseconds" file has been updated to incorporate the most
4709  recent International Earth Rotation and Reference Systems Service
4710  (IERS) bulletin.
4711
4712  There's an addition to tz-art.htm regarding the television show "Medium".
4713
4714
4715Release 2007f - 2007-05-07 10:46:46 -0400
4716
4717  changes by Paul Eggert (including Haiti, Turks and Caicos, and New
4718  Zealand)
4719
4720  changes to zic.c to allow hour values greater than 24 (along with
4721  Paul's improved time value overflow checking)
4722
4723
4724Release 2007e - 2007-04-02 10:11:52 -0400
4725
4726  Syria and Honduras changes by Paul Eggert
4727
4728  zic.c variable renaming changes by Arthur David Olson
4729
4730
4731Release 2007d - 2007-03-20 08:48:30 -0400
4732
4733  changes by Paul Eggert
4734
4735  the elimination of white space at the ends of lines
4736
4737
4738Release 2007c - 2007-02-26 09:09:37 -0500
4739
4740  changes by Paul Eggert
4741
4742
4743Release 2007b - 2007-02-12 09:34:20 -0500
4744
4745  Paul Eggert's proposed change to the quotation handling logic in zic.c.
4746
4747  changes to the commentary in "leapseconds" reflecting the IERS
4748  announcement that there is to be no positive leap second at the end
4749  of June 2007.
4750
4751
4752Release 2007a - 2007-01-08 12:28:29 -0500
4753
4754  changes by Paul Eggert
4755
4756  Derick Rethans's Asmara change
4757
4758  Oscar van Vlijmen's Easter Island local mean time change
4759
4760  symbolic link changes
4761
4762
4763Release 2006p - 2006-11-27 08:54:27 -0500
4764
4765  changes by Paul Eggert
4766
4767
4768Release 2006o - 2006-11-06 09:18:07 -0500
4769
4770  changes by Paul Eggert
4771
4772
4773Release 2006n - 2006-10-10 11:32:06 -0400
4774
4775  changes by Paul Eggert
4776
4777
4778Release 2006m - 2006-10-02 15:32:35 -0400
4779
4780  changes for Uruguay, Palestine, and Egypt by Paul Eggert
4781
4782  (minimalist) changes to zic.8 to clarify "until" information
4783
4784
4785Release data2006l - 2006-09-18 12:58:11 -0400
4786
4787  Paul's best-effort work on this coming weekend's Egypt time change
4788
4789
4790Release 2006k - 2006-08-28 12:19:09 -0400
4791
4792  changes by Paul Eggert
4793
4794
4795Release 2006j - 2006-08-21 09:56:32 -0400
4796
4797  changes by Paul Eggert
4798
4799
4800Release code2006i - 2006-08-07 12:30:55 -0400
4801
4802  localtime.c fixes
4803
4804  Ken Pizzini's conversion script
4805
4806
4807Release code2006h - 2006-07-24 09:19:37 -0400
4808
4809  adds public domain notices to four files
4810
4811  includes a fix for transition times being off by a second
4812
4813  adds a new recording to the "arts" file (information courtesy Colin Bowern)
4814
4815
4816Release 2006g - 2006-05-08 17:18:09 -0400
4817
4818  northamerica changes by Paul Eggert
4819
4820
4821Release 2006f - 2006-05-01 11:46:00 -0400
4822
4823  a missing version number problem is fixed (with thanks to Bradley
4824  White for catching the problem)
4825
4826
4827Release 2006d - 2006-04-17 14:33:43 -0400
4828
4829  changes by Paul Eggert
4830
4831  added new items to tz-arts.htm that were found by Paul
4832
4833
4834Release 2006c - 2006-04-03 10:09:32 -0400
4835
4836  two sets of data changes by Paul Eggert
4837
4838  a fencepost error fix in zic.c
4839
4840  changes to zic.c and the "europe" file to minimize differences
4841  between output produced by the old 32-bit zic and the new 64-bit
4842  version
4843
4844
4845Release 2006b - 2006-02-20 10:08:18 -0500
4846  [tz32code2006b + tz64code2006b + tzdata2006b]
4847
4848  64-bit code
4849
4850  All SCCS IDs were bumped to "8.1" for this release.
4851
4852
4853Release 2006a - 2006-01-30 08:59:31 -0500
4854
4855  changes by Paul Eggert (in particular, Indiana time zone moves)
4856
4857  an addition to the zic manual page to describe how special-case
4858  transitions are handled
4859
4860
4861Release 2005r - 2005-12-27 09:27:13 -0500
4862
4863  Canadian changes by Paul Eggert
4864
4865  They also add "<pre>" directives to time zone data files and reflect
4866  changes to warning message logic in "zdump.c" (but with calls to
4867  "gettext" kept unbundled at the suggestion of Ken Pizzini).
4868
4869
4870Release 2005q - 2005-12-13 09:17:09 -0500
4871
4872  Nothing earth-shaking here:
4873	1.  Electronic mail addresses have been removed.
4874	2.  Casts of the return value of exit have been removed.
4875	3.  Casts of the argument of is.* macros have been added.
4876	4.  Indentation in one section of zic.c has been fixed.
4877	5.  References to dead URLs in the data files have been dealt with.
4878
4879
4880Release 2005p - 2005-12-05 10:30:53 -0500
4881
4882  "systemv", "tz-link.htm", and "zdump.c" changes
4883  (less the casts of arguments to the is* macros)
4884
4885
4886Release 2005o - 2005-11-28 10:55:26 -0500
4887
4888  Georgia, Cuba, Nicaragua, and Jordan changes by Paul Eggert
4889
4890  zdump.c lint fixes by Arthur David Olson
4891
4892
4893Release 2005n - 2005-10-03 09:44:09 -0400
4894
4895  changes by Paul Eggert (both the Uruguay changes and the Kyrgyzstan
4896  et al. changes)
4897
4898
4899Release 2005m - 2005-08-29 12:15:40 -0400
4900
4901  changes by Paul Eggert (with a small tweak to the tz-art change)
4902
4903  a declaration of an unused variable has been removed from zdump.c
4904
4905
4906Release 2005l - 2005-08-22 12:06:39 -0400
4907
4908  changes by Paul Eggert
4909
4910  overflow/underflow checks by Arthur David Olson, minus changes to
4911  the "Theory" file about the pending addition of 64-bit data (I grow
4912  less confident of the changes being accepted with each passing day,
4913  and the changes no longer increase the data files nine-fold--there's
4914  less than a doubling in size by my local Sun's reckoning)
4915
4916
4917Release 2005k - 2005-07-14 14:14:24 -0400
4918
4919  The "leapseconds" file has been edited to reflect the recently
4920  announced leap second at the end of 2005.
4921
4922  I've also deleted electronic mail addresses from the files as an
4923  anti-spam measure.
4924
4925
4926Release 2005j - 2005-06-13 14:34:13 -0400
4927
4928  These reflect changes to limit the length of time zone abbreviations
4929  and the characters used in those abbreviations.
4930
4931  There are also changes to handle POSIX-style "quoted" timezone
4932  environment variables.
4933
4934  The changes were circulated on the time zone mailing list; the only
4935  change since then was the removal of a couple of minimum-length of
4936  abbreviation checks.
4937
4938
4939Release data2005i - 2005-04-21 15:04:16 -0400
4940
4941  changes (most importantly to Nicaragua and Haiti) by Paul Eggert
4942
4943
4944Release 2005h - 2005-04-04 11:24:47 -0400
4945
4946  changes by Paul Eggert
4947
4948  minor changes to Makefile and zdump.c to produce more useful output
4949  when doing a "make typecheck"
4950
4951
4952Release 2005g - 2005-03-14 10:11:21 -0500
4953
4954  changes by Paul Eggert (a change to current DST rules in Uruguay and
4955  an update to a link to time zone software)
4956
4957
4958Release 2005f - 2005-03-01 08:45:32 -0500
4959
4960  data and documentation changes by Paul Eggert
4961
4962
4963Release 2005e - 2005-02-10 15:59:44 -0500
4964
4965  [not summarized]
4966
4967
4968Release code2005d - 2005-01-31 09:21:47 -0500
4969
4970  make zic complain about links to links if the -v flag is used
4971
4972  have "make public" do more code checking
4973
4974  add an include to "localtime.c" for the benefit of gcc systems
4975
4976
4977Release 2005c - 2005-01-17 18:36:29 -0500
4978
4979  get better results when mktime runs on a system where time_t is double
4980
4981  changes to the data files (most importantly to Paraguay)
4982
4983
4984Release 2005b - 2005-01-10 09:19:54 -0500
4985
4986  Get localtime and gmtime working on systems with exotic time_t types.
4987
4988  Update the leap second commentary in the "leapseconds" file.
4989
4990
4991Release 2005a - 2005-01-01 13:13:44 -0500
4992
4993  [not summarized]
4994
4995
4996Release code2004i - 2004-12-14 13:42:58 -0500
4997
4998  Deal with systems where time_t is unsigned.
4999
5000
5001Release code2004h - 2004-12-07 11:40:18 -0500
5002
5003  64-bit-time_t changes
5004
5005
5006Release 2004g - 2004-11-02 09:06:01 -0500
5007
5008  update to Cuba (taking effect this weekend)
5009
5010  other changes by Paul Eggert
5011
5012  correction of the spelling of Oslo
5013
5014  changed versions of difftime.c and private.h
5015
5016
5017Release code2004f - 2004-10-21 10:25:22 -0400
5018
5019  Cope with wide-ranging tm_year values.
5020
5021
5022Release 2004e - 2004-10-11 14:47:21 -0400
5023
5024  Brazil/Argentina/Israel changes by Paul Eggert
5025
5026  changes to tz-link.htm by Paul
5027
5028  one small fix to Makefile
5029
5030
5031Release 2004d - 2004-09-22 08:27:29 -0400
5032
5033  Avoid overflow problems when TM_YEAR_BASE is added to an integer.
5034
5035
5036Release 2004c - 2004-08-11 12:06:26 -0400
5037
5038  asctime-related changes
5039
5040  (variants of) some of the documentation changes suggested by Paul Eggert
5041
5042
5043Release 2004b - 2004-07-19 14:33:35 -0400
5044
5045  data changes by Paul Eggert - most importantly, updates for Argentina
5046
5047
5048Release 2004a - 2004-05-27 12:00:47 -0400
5049
5050  changes by Paul Eggert
5051
5052  Handle DST transitions that occur at the end of a month in some
5053  years but at the start of the following month in other years.
5054
5055  Add a copy of the correspondence that's the basis for claims about
5056  DST in the Navajo Nation.
5057
5058
5059Release 2003e - 2003-12-15 09:36:47 -0500
5060
5061  changes by Arthur David Olson (primarily code changes)
5062
5063  changes by Paul Eggert (primarily data changes)
5064
5065  minor changes to "Makefile" and "northamerica" (in the latter case,
5066  optimization of the "Toronto" rules)
5067
5068
5069Release 2003d - 2003-10-06 09:34:44 -0400
5070
5071  changes by Paul Eggert
5072
5073
5074Release 2003c - 2003-09-16 10:47:05 -0400
5075
5076  Fix bad returns in zic.c's inleap function.
5077  Thanks to Bradley White for catching the problem!
5078
5079
5080Release 2003b - 2003-09-16 07:13:44 -0400
5081
5082  Add a "--version" option (and documentation) to the zic and zdump commands.
5083
5084  changes to overflow/underflow checking in zic
5085
5086  a localtime typo fix.
5087
5088  Update the leapseconds and tz-art.htm files.
5089
5090
5091Release 2003a - 2003-03-24 09:30:54 -0500
5092
5093  changes by Paul Eggert
5094
5095  a few additions and modifications to the tz-art.htm file
5096
5097
5098Release 2002d - 2002-10-15 13:12:42 -0400
5099
5100  changes by Paul Eggert, less the "Britain (UK)" change in iso3166.tab
5101
5102  There's also a new time zone quote in "tz-art.htm".
5103
5104
5105Release 2002c - 2002-04-04 11:55:20 -0500
5106
5107  changes by Paul Eggert
5108
5109  Change zic.c to avoid creating symlinks to files that don't exist.
5110
5111
5112Release 2002b - 2002-01-28 12:56:03 -0500
5113
5114  [These change notes are for Release 2002a, which was corrupted.
5115  2002b was a corrected version of 2002a.]
5116
5117  changes by Paul Eggert
5118
5119  Update the "leapseconds" file to note that there'll be no leap
5120  second at the end of June, 2002.
5121
5122  Change "zic.c" to deal with a problem in handling the "Asia/Bishkek" zone.
5123
5124  Change to "difftime.c" to avoid sizeof problems.
5125
5126
5127Release 2001d - 2001-10-09 13:31:32 -0400
5128
5129  changes by Paul Eggert
5130
5131
5132Release 2001c - 2001-06-05 13:59:55 -0400
5133
5134  changes by Paul Eggert and Andrew Brown
5135
5136
5137Release 2001b - 2001-04-05 16:44:38 -0400
5138
5139  changes by Paul Eggert (modulo jnorgard's typo fix)
5140
5141  tz-art.htm has been HTMLified.
5142
5143
5144Release 2001a - 2001-03-13 12:57:44 -0500
5145
5146  changes by Paul Eggert
5147
5148  An addition to the "leapseconds" file: comments with the text of the
5149  latest IERS leap second notice.
5150
5151  Trailing white space has been removed from data file lines, and
5152  repeated spaces in "Rule Jordan" lines in the "asia" file have been
5153  converted to tabs.
5154
5155
5156Release 2000h - 2000-12-14 15:33:38 -0500
5157
5158  changes by Paul Eggert
5159
5160  one typo fix in the "art" file
5161
5162  With providence, this is the last update of the millennium.
5163
5164
5165Release 2000g - 2000-10-10 11:35:22 -0400
5166
5167  changes by Paul Eggert
5168
5169  correction of John Mackin's name submitted by Robert Elz
5170
5171  Garry Shandling's Daylight Saving Time joke (!?!) from the recent
5172  Emmy Awards broadcast.
5173
5174
5175Release 2000f - 2000-08-10 09:31:58 -0400
5176
5177  changes by Paul Eggert
5178
5179  Added information in "tz-art.htm" on a Seinfeld reference to DST.
5180
5181  Error checking and messages in the "yearistype" script have been
5182  improved.
5183
5184
5185Release 2000e - 2000-07-31 09:27:54 -0400
5186
5187  data changes by Paul Eggert
5188
5189  a change to the default value of the defined constant HAVE_STRERROR
5190
5191  the addition of a Dave Barry quote on DST to the tz-arts file
5192
5193
5194Release 2000d - 2000-04-20 15:43:04 -0400
5195
5196  changes to the documentation and code of strftime for C99 conformance
5197
5198  a bug fix for date.c
5199
5200  These are based on (though modified from) changes by Paul Eggert.
5201
5202
5203Release 2000c - 2000-03-04 10:31:43 -0500
5204
5205  changes by Paul Eggert
5206
5207
5208Release 2000b - 2000-02-21 12:16:29 -0500
5209
5210  changes by Paul Eggert and Joseph Myers
5211
5212  modest tweaks to the tz-art.htm and tz-link.htm files
5213
5214
5215Release 2000a - 2000-01-18 09:21:26 -0500
5216
5217  changes by Paul Eggert
5218
5219  The two hypertext documents have also been renamed.
5220
5221
5222Release code1999i-data1999j - 1999-11-15 18:43:22 -0500
5223
5224  Paul Eggert's changes
5225
5226  additions to the "zic" manual page and the "Arts.htm" file
5227
5228
5229Release code1999h-data1999i - 1999-11-08 14:55:21 -0500
5230
5231  [not summarized]
5232
5233
5234Release data1999h - 1999-10-07 03:50:29 -0400
5235
5236  changes by Paul Eggert to "europe" (most importantly, fixing
5237  Lithuania and Estonia)
5238
5239
5240Release 1999g - 1999-09-28 11:06:18 -0400
5241
5242  data changes by Paul Eggert (most importantly, the change for
5243  Lebanon that buys correctness for this coming Sunday)
5244
5245  The "code" file contains changes to "Makefile" and "checktab.awk" to
5246  allow better checking of time zone files before they are published.
5247
5248
5249Release 1999f - 1999-09-23 09:48:14 -0400
5250
5251  changes by Arthur David Olson and Paul Eggert
5252
5253
5254Release 1999e - 1999-08-17 15:20:54 -0400
5255
5256  changes circulated by Paul Eggert, although the change to handling
5257  of DST-specifying timezone names has been commented out for now
5258  (search for "XXX" in "localtime.c" for details).  These files also
5259  do not make any changes to the start of DST in Brazil.
5260
5261  In addition to Paul's changes, there are updates to "Arts.htm" and
5262  cleanups of URLs.
5263
5264
5265Release 1999d - 1999-03-30 11:31:07 -0500
5266
5267  changes by Paul Eggert
5268
5269  The Makefile's "make public" rule has also been changed to do a test
5270  compile of each individual time zone data file (which should help
5271  avoid problems such as the one we had with Nicosia).
5272
5273
5274Release 1999c - 1999-03-25 09:47:47 -0500
5275
5276  changes by Paul Eggert, most importantly the change for Chile.
5277
5278
5279Release 1999b - 1999-02-01 17:51:44 -0500
5280
5281  changes by Paul Eggert
5282
5283  code changes (suggested by Mani Varadarajan, mani at be.com) for
5284  correct handling of symbolic links when building using a relative directory
5285
5286  code changes to generate correct messages for failed links
5287
5288  updates to the URLs in Arts.htm
5289
5290
5291Release 1999a - 1999-01-19 16:20:29 -0500
5292
5293  error message internationalizations and corrections in zic.c and
5294  zdump.c (as suggested by Vladimir Michl, vladimir.michl at upol.cz,
5295  to whom thanks!)
5296
5297
5298Release code1998h-data1998i - 1998-10-01 09:56:10 -0400
5299
5300  changes for Brazil, Chile, and Germany
5301
5302  support for use of "24:00" in the input files for the time zone compiler
5303
5304
5305Release code1998g-data1998h - 1998-09-24 10:50:28 -0400
5306
5307  changes by Paul Eggert
5308
5309  correction to a define in the "private.h" file
5310
5311
5312Release data1998g - 1998-08-11 03:28:35 -0000
5313  [tzdata1998g.tar.gz is missing!]
5314
5315  Lithuanian change provided by mgedmin at pub.osf.it
5316
5317  Move creation of the GMT link with Etc/GMT to "etcetera" (from
5318  "backward") to ensure that the GMT file is created even where folks
5319  don't want the "backward" links (as suggested by Paul Eggert).
5320
5321
5322Release data1998f - 1998-07-20 13:50:00 -0000
5323  [tzdata1998f.tar.gz is missing!]
5324
5325  Update the "leapseconds" file to include the newly-announced
5326  insertion at the end of 1998.
5327
5328
5329Release code1998f - 1998-06-01 10:18:31 -0400
5330
5331  addition to localtime.c by Guy Harris
5332
5333
5334Release 1998e - 1998-05-28 09:56:26 -0400
5335
5336  The Makefile is changed to produce zoneinfo-posix rather than
5337  zoneinfo/posix, and to produce zoneinfo-leaps rather than
5338  zoneinfo/right.
5339
5340  data changes by Paul Eggert
5341
5342  changes from Guy Harris to provide asctime_r and ctime_r
5343
5344  A usno1998 file (substantially identical to usno1997) has been added.
5345
5346
5347Release 1998d - 1998-05-14 11:58:34 -0400
5348
5349  changes to comments (in particular, elimination of references to CIA maps).
5350  "Arts.htm", "WWW.htm", "asia", and "australasia" are the only places
5351  where changes occur.
5352
5353
5354Release 1998c - 1998-02-28 12:32:26 -0500
5355
5356  changes by Paul Eggert (save the "French correction," on which I'll
5357  wait for the dust to settle)
5358
5359  symlink changes
5360
5361  changes and additions to Arts.htm
5362
5363
5364Release 1998b - 1998-01-17 14:31:51 -0500
5365
5366  URL cleanups and additions
5367
5368
5369Release 1998a - 1998-01-13 12:37:35 -0500
5370
5371  changes by Paul Eggert
5372
5373
5374Release code1997i-data1997k - 1997-12-29 09:53:41 -0500
5375
5376  changes by Paul Eggert, with minor modifications from Arthur David
5377  Olson to make the files more browser friendly
5378
5379
5380Release code1997h-data1997j - 1997-12-18 17:47:35 -0500
5381
5382  minor changes to put "TZif" at the start of each timezone information file
5383
5384  a rule has also been added to the Makefile so you can
5385	make zones
5386  to just recompile the zone information files (rather than doing a
5387  full "make install" with its other effects).
5388
5389
5390Release data1997i - 1997-10-07 08:45:38 -0400
5391
5392  changes to Africa by Paul Eggert
5393
5394
5395Release code1997g-data1997h - 1997-09-04 16:56:54 -0400
5396
5397  corrections for Uruguay (and other locations)
5398
5399  Arthur David Olson's simple-minded fix allowing mktime to both
5400  correctly handle leap seconds and correctly handle tm_sec values
5401  upon which arithmetic has been performed.
5402
5403
5404Release code1997f-data1997g - 1997-07-19 13:15:02 -0400
5405
5406  Paul Eggert's updates
5407
5408  a small change to a function prototype;
5409
5410  "Music" has been renamed "Arts.htm", HTMLified, and augmented to
5411  include information on Around the World in Eighty Days.
5412
5413
5414Release code1997e-data1997f - 1997-05-03 18:52:34 -0400
5415
5416  fixes to zic's error handling
5417
5418  changes inspired by the item circulated on Slovenia
5419
5420  The description of Web resources has been HTMLified for browsing
5421  convenience.
5422
5423  A new piece of tz-related music has been added to the "Music" file.
5424
5425
5426Release code1997d-data1997e - 1997-03-29 12:48:52 -0500
5427
5428  Paul Eggert's latest suggestions
5429
5430
5431Release code1997c-data1997d - 1997-03-07 20:37:54 -0500
5432
5433  changes to "zic.c" to correct performance of the "-s" option
5434
5435  a new file "usno1997"
5436
5437
5438Release data1997c - 1997-03-04 09:58:18 -0500
5439
5440  changes in Israel
5441
5442
5443Release 1997b - 1997-02-27 18:34:19 -0500
5444
5445  The data file incorporates the 1997 leap second.
5446
5447  The code file incorporates Arthur David Olson's take on the
5448  zic/multiprocessor/directory-creation situation.
5449
5450
5451Release 1997a - 1997-01-21 09:11:10 -0500
5452
5453  Paul Eggert's Antarctica (and other changes)
5454
5455  Arthur David Olson finessed the "getopt" issue by checking against
5456  both -1 and EOF (regardless of POSIX, SunOS 4.1.1's manual says -1
5457  is returned while SunOS 5.5's manual says EOF is returned).
5458
5459
5460Release code1996o-data1996n - 1996-12-27 21:42:05 -0500
5461
5462  Paul Eggert's latest changes
5463
5464
5465Release code1996n - 1996-12-16 09:42:02 -0500
5466
5467  link snapping fix from Bruce Evans (via Garrett Wollman)
5468
5469
5470Release data1996m - 1996-11-24 02:37:34 -0000
5471  [tzdata1996m.tar.gz is missing!]
5472
5473  Paul Eggert's batch of changes
5474
5475
5476Release code1996m-data1996l - 1996-11-05 14:00:12 -0500
5477
5478  No functional changes here; the files have simply been changed to
5479  make more use of ISO style dates in comments. The names of the above
5480  files now include the year in full.
5481
5482
5483Release code96l - 1996-09-08 17:12:20 -0400
5484
5485  tzcode96k was missing a couple of pieces.
5486
5487
5488Release 96k - 1996-09-08 16:06:22 -0400
5489
5490  the latest round of changes from Paul Eggert
5491
5492  the recent Year 2000 material
5493
5494
5495Release code96j - 1996-07-30 13:18:53 -0400
5496
5497  Set sp->typecnt as suggested by Timothy Patrick Murphy.
5498
5499
5500Release code96i - 1996-07-27 20:11:35 -0400
5501
5502  Paul's suggested patch for strftime %V week numbers
5503
5504
5505Release data96i - 1996-07-01 18:13:04 -0400
5506
5507  "northamerica" and "europe" changes by Paul Eggert
5508
5509
5510Release code96h - 1996-06-05 08:02:21 -0400
5511
5512  fix for handling transitions specified in Universal Time
5513
5514  Some "public domain" notices have also been added.
5515
5516
5517Release code96g - 1996-05-16 14:00:26 -0400
5518
5519  fix for the simultaneous-DST-and-zone-change challenge
5520
5521
5522Release data96h - 1996-05-09 17:40:51 -0400
5523
5524  changes by Paul Eggert
5525
5526
5527Release code96f-data96g - 1996-05-03 03:09:59 -0000
5528  [tzcode96f.tar.gz + tzdata96g.tar.gz are both missing!]
5529
5530  The changes get us some of the way to fixing the problems noted in Paul
5531  Eggert's letter yesterday (in addition to a few others).  The approach
5532  has been to make zic a bit smarter about figuring out what time zone
5533  abbreviations apply just after the time specified in the "UNTIL" part
5534  of a zone line.  Putting the smarts in zic means avoiding having
5535  transition times show up in both "Zone" lines and "Rule" lines, which
5536  in turn avoids multiple transition time entries in time zone files.
5537  (This also makes the zic input files such as "europe" a bit shorter and
5538  should ease maintenance.)
5539
5540
5541Release data96f - 1996-04-19 19:20:03 -0000
5542  [tzdata96f.tar.gz is missing!]
5543
5544  The only changes are to the "northamerica" file; the time zone
5545  abbreviation for Denver is corrected to MST (and MDT), and the
5546  comments for Mexico have been updated.
5547
5548
5549Release data96e - 1996-03-19 17:37:26 -0500
5550
5551  Proposals by Paul Eggert, in particular the Portugal change that
5552  comes into play at the end of this month.
5553
5554
5555Release data96d - 1996-03-18 20:49:39 -0500
5556
5557  [not summarized]
5558
5559
5560Release code96e - 1996-02-29 15:43:27 -0000
5561  [tzcode96e.tar.gz is missing!]
5562
5563  internationalization changes and the fix to the documentation for strftime
5564
5565
5566Release code96d-data96c - 1996-02-12 11:05:27 -0500
5567
5568  The "code" file simply updates Bob Kridle's electronic address.
5569
5570  The "data" file updates rules for Mexico.
5571
5572
5573Release data96b - 1996-01-27 15:44:42 -0500
5574
5575  Kiribati change
5576
5577
5578Release code96c - 1996-01-16 16:58:15 -0500
5579
5580  leap-year streamlining and binary-search changes
5581
5582  fix to newctime.3
5583
5584
5585Release code96b - 1996-01-10 20:42:39 -0500
5586
5587  fixes and enhancements from Paul Eggert, including code that
5588  emulates the behavior of recent versions of the SunOS "date"
5589  command.
5590
5591
5592Release 96a - 1996-01-06 09:08:24 -0500
5593
5594  Israel updates
5595
5596  fixes to strftime.c for correct ISO 8601 week number generation,
5597  plus support for two new formats ('G' and 'g') to give ISO 8601 year
5598  numbers (which are not necessarily the same as calendar year numbers)
5599
5600
5601Release code95i-data95m - 1995-12-21 12:46:47 -0500
5602
5603  The latest revisions from Paul Eggert are included, the usno1995
5604  file has been updated, and a new file ("WWW") covering useful URLs
5605  has been added.
5606
5607
5608Release code95h-data95l - 1995-12-19 18:10:12 -0500
5609
5610  A simplification of a macro definition, a change to data for Sudan,
5611  and (for last minute shoppers) notes in the "Music" file on the CD
5612  "Old Man Time".
5613
5614
5615Release code95g-data95k - 1995-10-30 10:32:47 -0500
5616
5617  (slightly reformatted) 8-bit-clean proposed patch
5618
5619  minor patch: US/Eastern -> America/New_York
5620
5621  snapshot of the USNO's latest data ("usno1995")
5622
5623  some other minor cleanups
5624
5625
5626Release code95f-data95j - 1995-10-28 21:01:34 -0000
5627  [tzcode95f.tar.gz + tzdata95j.tar.gz are both missing!]
5628
5629  European cleanups
5630
5631  support for 64-bit time_t's
5632
5633  optimization in localtime.c
5634
5635
5636Release code95e - 1995-10-13 13:23:57 -0400
5637
5638  the mktime change to scan from future to past when trying to find time zone
5639  offsets
5640
5641
5642Release data95i - 1995-09-26 10:43:26 -0400
5643
5644  For Canada/Central, guess that the Sun customer's "one week too
5645  early" was just a approximation, and the true error is one month
5646  too early.  This is consistent with the rest of Canada.
5647
5648
5649Release data95h - 1995-09-21 11:26:48 -0400
5650
5651  latest changes from Paul Eggert
5652
5653
5654Release code95d - 1995-09-14 11:14:45 -0400
5655
5656  the addition of a "Music" file, which documents four recorded
5657  versions of the tune "Save That Time".
5658
5659
5660Release data95g - 1995-09-01 17:21:36 -0400
5661
5662  "yearistype" correction
5663
5664
5665Release data95f - 1995-08-28 20:46:56 -0400
5666
5667  Paul Eggert's change to the australasia file
5668
5669
5670Release data95e - 1995-07-08 18:02:34 -0400
5671
5672  The only change is a leap second at the end of this year.
5673  Thanks to Bradley White for forwarding news on the leap second.
5674
5675
5676Release data95d - 1995-07-03 13:26:22 -0400
5677
5678  Paul Eggert's changes
5679
5680
5681Release data95c - 1995-07-02 19:19:28 -0400
5682
5683  changes to "asia", "backward", "europe", and "southamerica"
5684  (read: northamericacentrics need not apply)
5685
5686
5687Release code95c - 1995-03-13 14:00:46 -0500
5688
5689  one-line fix for sign extension problems in detzcode
5690
5691
5692Release 95b - 1995-03-04 11:22:38 -0500
5693
5694  Minor changes in both:
5695
5696  The "code" file contains a workaround for the lack of "unistd.h" in
5697  Microsoft C++ version 7.
5698
5699  The "data" file contains a fixed "Link" for America/Shiprock.
5700
5701
5702Release 94h - 1994-12-10 12:51:14 -0500
5703
5704  The files:
5705
5706  *	incorporate the changes to "zdump" and "date" to make changes to
5707	the "TZ" environment variable permanent;
5708
5709  *	incorporate the table changes by Paul Eggert;
5710
5711  *	include (and document) support for universal time specifications in
5712	data files - but do not (yet) include use of this feature in the
5713	data files.
5714
5715  Think of this as "TZ Classic" - the software has been set up not to break if
5716  universal time shows up in its input, and data entries have been
5717  left as is so as not to break existing implementations.
5718
5719
5720Release data94f - 1994-08-20 12:56:09 -0400
5721
5722  (with thanks!) the latest data updates from Paul Eggert
5723
5724
5725Release data94e - 1994-06-04 13:13:53 -0400
5726
5727  [not summarized]
5728
5729
5730Release code94g - 1994-05-05 12:14:07 -0400
5731
5732  fix missing "optind.c" and a reference to it in the Makefile
5733
5734
5735Release code94f - 1994-05-05 13:00:33 -0000
5736  [tzcode94f.tar.gz is missing!]
5737
5738  changes to avoid overflow in difftime, as well as changes to cope
5739  with the 52/53 challenge in strftime
5740
5741
5742Release code94e - 1994-03-30 23:32:59 -0500
5743
5744  change for the benefit of PCTS
5745
5746
5747Release 94d - 1994-02-24 15:42:25 -0500
5748
5749  Avoid clashes with POSIX semantics for zones such as GMT+4.
5750
5751  Some other very minor housekeeping is also present.
5752
5753
5754Release code94c - 1994-02-10 08:52:40 -0500
5755
5756  Fix bug where mkdirs was broken unless you compile with
5757  -fwritable-strings (which is generally losing to do).
5758
5759
5760Release 94b - 1994-02-07 10:04:33 -0500
5761
5762  work by Paul Eggert who notes:
5763
5764  I found another book of time zone histories by E W Whitman; it's not
5765  as extensive as Shanks but has a few goodies of its own.  I used it
5766  to update the tables.  I also fixed some more as a result of
5767  correspondence with Adam David and Peter Ilieve, and move some stray
5768  links from 'europe' to 'backward'.  I corrected some scanning errors
5769  in usno1989.
5770
5771  As far as the code goes, I fixed zic to allow years in the range
5772  INT_MIN to INT_MAX; this fixed a few boundary conditions around 1900.
5773  And I cleaned up the zic documentation a little bit.
5774
5775
5776Release data94a - 1994-02-03 08:58:54 -0500
5777
5778  It simply incorporates the recently announced leap second into the
5779  "leapseconds" file.
5780
5781
5782Release 93g - 1993-11-22 17:28:27 -0500
5783
5784  Paul Eggert has provided a good deal of historic information (based
5785  on Shanks), and there are some code changes to deal with the buglets
5786  that crawled out in dealing with the new information.
5787
5788
5789Release 93f - 1993-10-15 12:27:46 -0400
5790
5791  Paul Eggert's changes
5792
5793
5794Release 93e - 1993-09-05 21:21:44 -0400
5795
5796  This has updated data for Israel, England, and Kwajalein.  There's
5797  also an update to "zdump" to cope with Kwajalein's 24-hour jump.
5798  Thanks to Paul Eggert and Peter Ilieve for the changes.
5799
5800
5801Release 93d - 1993-06-17 23:34:17 -0400
5802
5803  new fix and new data on Israel
5804
5805
5806Release 93c - 1993-06-06 19:31:55 -0400
5807
5808  [not summarized]
5809
5810
5811Release 93b - 1993-02-02 14:53:58 -0500
5812
5813  updated "leapseconds" file
5814
5815
5816Release 93 - 1993-01-08 07:01:06 -0500
5817
5818  At kre's suggestion, the package has been split in two - a code piece
5819  (which also includes documentation) that's only of use to folks who
5820  want to recompile things and a data piece useful to anyone who can
5821  run "zic".
5822
5823  The new version has a few changes to the data files, a few
5824  portability changes, and an off-by-one fix (with thanks to
5825  Tom Karzes at deshaw.com for providing a description and a
5826  solution).
5827
5828
5829Release 92c - 1992-11-21 17:35:36 -0000
5830  [tz92c.tar.Z is missing!]
5831
5832  The fallout from the latest round of DST transitions.
5833
5834  There are changes for Portugal, Saskatchewan, and "Pacific-New";
5835  there's also a change to "zic.c" that makes it portable to more systems.
5836
5837
5838Release 92 - 1992-04-25 18:17:03 -0000
5839  [tz92.tar.Z is missing!]
5840
5841  By popular demand (well, at any rate, following a request by kre at munnari)
5842
5843
5844The 1989 update of the time zone package featured:
5845
5846  *	POSIXization (including interpretation of POSIX-style TZ environment
5847	variables, provided by Guy Harris),
5848  *	ANSIfication (including versions of "mktime" and "difftime"),
5849  *	SVIDulation (an "altzone" variable)
5850  *	MACHination (the "gtime" function)
5851  *	corrections to some time zone data (including corrections to the rules
5852	for Great Britain and New Zealand)
5853  *	reference data from the United States Naval Observatory for folks who
5854	want to do additional time zones
5855  *	and the 1989 data for Saudi Arabia.
5856
5857  (Since this code will be treated as "part of the implementation" in some
5858  places and as "part of the application" in others, there's no good way to
5859  name functions, such as timegm, that are not part of the proposed ANSI C
5860  standard; such functions have kept their old, underscore-free names in this
5861  update.)
5862
5863  And the "dysize" function has disappeared; it was present to allow
5864  compilation of the "date" command on old BSD systems, and a version of "date"
5865  is now provided in the package.  The "date" command is not created when you
5866  "make all" since it may lack options provided by the version distributed with
5867  your operating system, or may not interact with the system in the same way
5868  the native version does.
5869
5870  Since POSIX frowns on correct leap second handling, the default behavior of
5871  the "zic" command (in the absence of a "-L" option) has been changed to omit
5872  leap second information from its output files.
5873
5874
5875-----
5876Notes
5877
5878This file contains copies of the part of each release announcement
5879that talks about the changes in that release.  The text has been
5880adapted and reformatted for the purposes of this file.
5881
5882Traditionally a release R consists of a pair of tarball files,
5883tzcodeR.tar.gz and tzdataR.tar.gz.  However, some releases (e.g.,
5884code2010a, data2012c) consist of just one or the other tarball, and a
5885few (e.g., code2012c-data2012d) have tarballs with mixed version
5886numbers.  Recent releases also come in an experimental format
5887consisting of a single tarball tzdb-R.tar.lz with extra data.
5888
5889Release timestamps are taken from the release's commit (for newer,
5890Git-based releases), from the newest file in the tarball (for older
5891releases, where this info is available) or from the email announcing
5892the release (if all else fails; these are marked with a time zone
5893abbreviation of -0000 and an "is missing!" comment).
5894
5895Earlier versions of the code and data were not announced on the tz
5896list and are not summarized here.
5897
5898This file is in the public domain.
5899
5900Local Variables:
5901coding: utf-8
5902End:
5903